- switching Node class and NodeInfo/Binfo to using slots

- memoizer subsystem now uses decorators instead of the metaclass approach

51 files changed, 1473 insertions, 809 deletions

diff --git a/src/engine/SCons/Action.py b/src/engine/SCons/Action.py
index eecea11..5a34825 100644
--- a/src/engine/SCons/Action.py
+++ b/src/engine/SCons/Action.py
@@ -540,7 +540,7 @@ class _ActionAction(ActionBase):
         if chdir:
             save_cwd = os.getcwd()
             try:
-                chdir = str(chdir.abspath)
+                chdir = str(chdir.get_abspath())
             except AttributeError:
                 if not is_String(chdir):
                     if executor:
diff --git a/src/engine/SCons/Builder.py b/src/engine/SCons/Builder.py
index c82f6ac..769b15d 100644
--- a/src/engine/SCons/Builder.py
+++ b/src/engine/SCons/Builder.py
@@ -352,11 +352,6 @@ class BuilderBase(object):
     nodes (files) from input nodes (files).
     """
 
-    if SCons.Memoize.use_memoizer:
-        __metaclass__ = SCons.Memoize.Memoized_Metaclass
-
-    memoizer_counters = []
-
     def __init__(self,  action = None,
                         prefix = '',
                         suffix = '',
@@ -758,8 +753,7 @@ class BuilderBase(object):
     def _get_src_builders_key(self, env):
         return id(env)
 
-    memoizer_counters.append(SCons.Memoize.CountDict('get_src_builders', _get_src_builders_key))
-
+    @SCons.Memoize.CountDictCall(_get_src_builders_key)
     def get_src_builders(self, env):
         """
         Returns the list of source Builders for this Builder.
@@ -795,8 +789,7 @@ class BuilderBase(object):
     def _subst_src_suffixes_key(self, env):
         return id(env)
 
-    memoizer_counters.append(SCons.Memoize.CountDict('subst_src_suffixes', _subst_src_suffixes_key))
-
+    @SCons.Memoize.CountDictCall(_subst_src_suffixes_key)
     def subst_src_suffixes(self, env):
         """
         The suffix list may contain construction variable expansions,
diff --git a/src/engine/SCons/BuilderTests.py b/src/engine/SCons/BuilderTests.py
index 70a7a3f..3eca588 100644
--- a/src/engine/SCons/BuilderTests.py
+++ b/src/engine/SCons/BuilderTests.py
@@ -163,7 +163,8 @@ class MyNode_without_target_from_source(object):
         self.builder = None
         self.is_explicit = None
         self.side_effect = 0
-        self.suffix = os.path.splitext(name)[1]
+    def get_suffix(self):
+        return os.path.splitext(self.name)[1]
     def disambiguate(self):
         return self
     def __str__(self):
@@ -349,7 +350,7 @@ class BuilderTestCase(unittest.TestCase):
 
         builder = SCons.Builder.Builder(action="foo")
         target = builder(env, None, source='n22', srcdir='src_dir')[0]
-        p = target.sources[0].path
+        p = target.sources[0].get_internal_path()
         assert p == os.path.join('src_dir', 'n22'), p
 
     def test_mistaken_variables(self):
@@ -487,20 +488,20 @@ class BuilderTestCase(unittest.TestCase):
         builder = SCons.Builder.Builder(prefix = 'lib', action='')
         assert builder.get_prefix(env) == 'lib'
         tgt = builder(env, target = 'tgt1', source = 'src1')[0]
-        assert tgt.path == 'libtgt1', \
-                "Target has unexpected name: %s" % tgt.path
+        assert tgt.get_internal_path() == 'libtgt1', \
+                "Target has unexpected name: %s" % tgt.get_internal_path()
         tgt = builder(env, target = 'tgt2a tgt2b', source = 'src2')[0]
-        assert tgt.path == 'libtgt2a tgt2b', \
-                "Target has unexpected name: %s" % tgt.path
+        assert tgt.get_internal_path() == 'libtgt2a tgt2b', \
+                "Target has unexpected name: %s" % tgt.get_internal_path()
         tgt = builder(env, target = None, source = 'src3')[0]
-        assert tgt.path == 'libsrc3', \
-                "Target has unexpected name: %s" % tgt.path
+        assert tgt.get_internal_path() == 'libsrc3', \
+                "Target has unexpected name: %s" % tgt.get_internal_path()
         tgt = builder(env, target = None, source = 'lib/src4')[0]
-        assert tgt.path == os.path.join('lib', 'libsrc4'), \
-                "Target has unexpected name: %s" % tgt.path
+        assert tgt.get_internal_path() == os.path.join('lib', 'libsrc4'), \
+                "Target has unexpected name: %s" % tgt.get_internal_path()
         tgt = builder(env, target = 'lib/tgt5', source = 'lib/src5')[0]
-        assert tgt.path == os.path.join('lib', 'libtgt5'), \
-                "Target has unexpected name: %s" % tgt.path
+        assert tgt.get_internal_path() == os.path.join('lib', 'libtgt5'), \
+                "Target has unexpected name: %s" % tgt.get_internal_path()
 
         def gen_prefix(env, sources):
             return "gen_prefix() says " + env['FOO']
@@ -520,17 +521,17 @@ class BuilderTestCase(unittest.TestCase):
                                                   '.zzz' : my_emit},
                                         action = '')
         tgt = builder(my_env, target = None, source = 'f1')[0]
-        assert tgt.path == 'default-f1', tgt.path
+        assert tgt.get_internal_path() == 'default-f1', tgt.get_internal_path()
         tgt = builder(my_env, target = None, source = 'f2.c')[0]
-        assert tgt.path == 'default-f2', tgt.path
+        assert tgt.get_internal_path() == 'default-f2', tgt.get_internal_path()
         tgt = builder(my_env, target = None, source = 'f3.in')[0]
-        assert tgt.path == 'out-f3', tgt.path
+        assert tgt.get_internal_path() == 'out-f3', tgt.get_internal_path()
         tgt = builder(my_env, target = None, source = 'f4.x')[0]
-        assert tgt.path == 'y-f4', tgt.path
+        assert tgt.get_internal_path() == 'y-f4', tgt.get_internal_path()
         tgt = builder(my_env, target = None, source = 'f5.foo')[0]
-        assert tgt.path == 'foo-f5', tgt.path
+        assert tgt.get_internal_path() == 'foo-f5', tgt.get_internal_path()
         tgt = builder(my_env, target = None, source = 'f6.zzz')[0]
-        assert tgt.path == 'emit-f6', tgt.path
+        assert tgt.get_internal_path() == 'emit-f6', tgt.get_internal_path()
 
     def test_set_suffix(self):
         """Test the set_suffix() method"""
@@ -560,13 +561,13 @@ class BuilderTestCase(unittest.TestCase):
         assert b1.src_suffixes(env) == ['.c'], b1.src_suffixes(env)
 
         tgt = b1(env, target = 'tgt2', source = 'src2')[0]
-        assert tgt.sources[0].path == 'src2.c', \
-                "Source has unexpected name: %s" % tgt.sources[0].path
+        assert tgt.sources[0].get_internal_path() == 'src2.c', \
+                "Source has unexpected name: %s" % tgt.sources[0].get_internal_path()
 
         tgt = b1(env, target = 'tgt3', source = 'src3a src3b')[0]
         assert len(tgt.sources) == 1
-        assert tgt.sources[0].path == 'src3a src3b.c', \
-                "Unexpected tgt.sources[0] name: %s" % tgt.sources[0].path
+        assert tgt.sources[0].get_internal_path() == 'src3a src3b.c', \
+                "Unexpected tgt.sources[0] name: %s" % tgt.sources[0].get_internal_path()
 
         b2 = SCons.Builder.Builder(src_suffix = '.2', src_builder = b1)
         r = sorted(b2.src_suffixes(env))
@@ -636,14 +637,14 @@ class BuilderTestCase(unittest.TestCase):
         builder = SCons.Builder.Builder(suffix = 'o', action='')
         assert builder.get_suffix(env) == '.o', builder.get_suffix(env)
         tgt = builder(env, target = 'tgt3', source = 'src3')[0]
-        assert tgt.path == 'tgt3.o', \
-                "Target has unexpected name: %s" % tgt.path
+        assert tgt.get_internal_path() == 'tgt3.o', \
+                "Target has unexpected name: %s" % tgt.get_internal_path()
         tgt = builder(env, target = 'tgt4a tgt4b', source = 'src4')[0]
-        assert tgt.path == 'tgt4a tgt4b.o', \
-                "Target has unexpected name: %s" % tgt.path
+        assert tgt.get_internal_path() == 'tgt4a tgt4b.o', \
+                "Target has unexpected name: %s" % tgt.get_internal_path()
         tgt = builder(env, target = None, source = 'src5')[0]
-        assert tgt.path == 'src5.o', \
-                "Target has unexpected name: %s" % tgt.path
+        assert tgt.get_internal_path() == 'src5.o', \
+                "Target has unexpected name: %s" % tgt.get_internal_path()
 
         def gen_suffix(env, sources):
             return "gen_suffix() says " + env['BAR']
@@ -663,17 +664,17 @@ class BuilderTestCase(unittest.TestCase):
                                                   '.zzz' : my_emit},
                                         action='')
         tgt = builder(my_env, target = None, source = 'f1')[0]
-        assert tgt.path == 'f1.default', tgt.path
+        assert tgt.get_internal_path() == 'f1.default', tgt.get_internal_path()
         tgt = builder(my_env, target = None, source = 'f2.c')[0]
-        assert tgt.path == 'f2.default', tgt.path
+        assert tgt.get_internal_path() == 'f2.default', tgt.get_internal_path()
         tgt = builder(my_env, target = None, source = 'f3.in')[0]
-        assert tgt.path == 'f3.out', tgt.path
+        assert tgt.get_internal_path() == 'f3.out', tgt.get_internal_path()
         tgt = builder(my_env, target = None, source = 'f4.x')[0]
-        assert tgt.path == 'f4.y', tgt.path
+        assert tgt.get_internal_path() == 'f4.y', tgt.get_internal_path()
         tgt = builder(my_env, target = None, source = 'f5.bar')[0]
-        assert tgt.path == 'f5.new', tgt.path
+        assert tgt.get_internal_path() == 'f5.new', tgt.get_internal_path()
         tgt = builder(my_env, target = None, source = 'f6.zzz')[0]
-        assert tgt.path == 'f6.emit', tgt.path
+        assert tgt.get_internal_path() == 'f6.emit', tgt.get_internal_path()
 
     def test_single_source(self):
         """Test Builder with single_source flag set"""
diff --git a/src/engine/SCons/CacheDir.py b/src/engine/SCons/CacheDir.py
index 9dd18e5..f32b326 100644
--- a/src/engine/SCons/CacheDir.py
+++ b/src/engine/SCons/CacheDir.py
@@ -50,11 +50,11 @@ def CacheRetrieveFunc(target, source, env):
     cd.CacheDebug('CacheRetrieve(%s):  retrieving from %s\n', t, cachefile)
     if SCons.Action.execute_actions:
         if fs.islink(cachefile):
-            fs.symlink(fs.readlink(cachefile), t.path)
+            fs.symlink(fs.readlink(cachefile), t.get_internal_path())
         else:
-            env.copy_from_cache(cachefile, t.path)
+            env.copy_from_cache(cachefile, t.get_internal_path())
         st = fs.stat(cachefile)
-        fs.chmod(t.path, stat.S_IMODE(st[stat.ST_MODE]) | stat.S_IWRITE)
+        fs.chmod(t.get_internal_path(), stat.S_IMODE(st[stat.ST_MODE]) | stat.S_IWRITE)
     return 0
 
 def CacheRetrieveString(target, source, env):
@@ -63,7 +63,7 @@ def CacheRetrieveString(target, source, env):
     cd = env.get_CacheDir()
     cachedir, cachefile = cd.cachepath(t)
     if t.fs.exists(cachefile):
-        return "Retrieved `%s' from cache" % t.path
+        return "Retrieved `%s' from cache" % t.get_internal_path()
     return None
 
 CacheRetrieve = SCons.Action.Action(CacheRetrieveFunc, CacheRetrieveString)
@@ -106,12 +106,12 @@ def CachePushFunc(target, source, env):
                 raise SCons.Errors.EnvironmentError(msg)
 
     try:
-        if fs.islink(t.path):
-            fs.symlink(fs.readlink(t.path), tempfile)
+        if fs.islink(t.get_internal_path()):
+            fs.symlink(fs.readlink(t.get_internal_path()), tempfile)
         else:
-            fs.copy2(t.path, tempfile)
+            fs.copy2(t.get_internal_path(), tempfile)
         fs.rename(tempfile, cachefile)
-        st = fs.stat(t.path)
+        st = fs.stat(t.get_internal_path())
         fs.chmod(cachefile, stat.S_IMODE(st[stat.ST_MODE]) | stat.S_IWRITE)
     except EnvironmentError:
         # It's possible someone else tried writing the file at the
diff --git a/src/engine/SCons/Debug.py b/src/engine/SCons/Debug.py
index 9974039..b47c24c 100644
--- a/src/engine/SCons/Debug.py
+++ b/src/engine/SCons/Debug.py
@@ -34,6 +34,7 @@ import os
 import sys
 import time
 import weakref
+import inspect
 
 # Global variable that gets set to 'True' by the Main script,
 # when the creation of class instances should get tracked.
@@ -46,7 +47,12 @@ def logInstanceCreation(instance, name=None):
         name = instance.__class__.__name__
     if name not in tracked_classes:
         tracked_classes[name] = []
-    tracked_classes[name].append(weakref.ref(instance))
+    if hasattr(instance, '__dict__'):
+        tracked_classes[name].append(weakref.ref(instance))
+    else:
+        # weakref doesn't seem to work when the instance
+        # contains only slots...
+        tracked_classes[name].append(instance)
 
 def string_to_classes(s):
     if s == '*':
@@ -66,7 +72,10 @@ def listLoggedInstances(classes, file=sys.stdout):
     for classname in string_to_classes(classes):
         file.write('\n%s:\n' % classname)
         for ref in tracked_classes[classname]:
-            obj = ref()
+            if inspect.isclass(ref):
+                obj = ref()
+            else:
+                obj = ref
             if obj is not None:
                 file.write('    %s\n' % repr(obj))
 
diff --git a/src/engine/SCons/Environment.py b/src/engine/SCons/Environment.py
index 5f2c9ff..fa019b8 100644
--- a/src/engine/SCons/Environment.py
+++ b/src/engine/SCons/Environment.py
@@ -365,9 +365,6 @@ class SubstitutionEnvironment(object):
     class actually becomes useful.)
     """
 
-    if SCons.Memoize.use_memoizer:
-        __metaclass__ = SCons.Memoize.Memoized_Metaclass
-
     def __init__(self, **kw):
         """Initialization of an underlying SubstitutionEnvironment class.
         """
@@ -902,8 +899,6 @@ class Base(SubstitutionEnvironment):
     Environment.
     """
 
-    memoizer_counters = []
-
     #######################################################################
     # This is THE class for interacting with the SCons build engine,
     # and it contains a lot of stuff, so we're going to try to keep this
@@ -1071,8 +1066,7 @@ class Base(SubstitutionEnvironment):
             factory = getattr(self.fs, name)
         return factory
 
-    memoizer_counters.append(SCons.Memoize.CountValue('_gsm'))
-
+    @SCons.Memoize.CountMethodCall
     def _gsm(self):
         try:
             return self._memo['_gsm']
@@ -1802,7 +1796,7 @@ class Base(SubstitutionEnvironment):
         self.Replace(**kw)
 
     def _find_toolpath_dir(self, tp):
-        return self.fs.Dir(self.subst(tp)).srcnode().abspath
+        return self.fs.Dir(self.subst(tp)).srcnode().get_abspath()
 
     def Tool(self, tool, toolpath=None, **kw):
         if SCons.Util.is_String(tool):
diff --git a/src/engine/SCons/EnvironmentTests.py b/src/engine/SCons/EnvironmentTests.py
index a0869e8..9a9d2b0 100644
--- a/src/engine/SCons/EnvironmentTests.py
+++ b/src/engine/SCons/EnvironmentTests.py
@@ -2703,25 +2703,25 @@ def generate(env):
         t = env.AlwaysBuild('a', 'b$FOO', ['c', 'd'], '$BAR',
                             env.fs.Dir('dir'), env.fs.File('file'))
         assert t[0].__class__.__name__ == 'Entry'
-        assert t[0].path == 'a'
+        assert t[0].get_internal_path() == 'a'
         assert t[0].always_build
         assert t[1].__class__.__name__ == 'Entry'
-        assert t[1].path == 'bfff'
+        assert t[1].get_internal_path() == 'bfff'
         assert t[1].always_build
         assert t[2].__class__.__name__ == 'Entry'
-        assert t[2].path == 'c'
+        assert t[2].get_internal_path() == 'c'
         assert t[2].always_build
         assert t[3].__class__.__name__ == 'Entry'
-        assert t[3].path == 'd'
+        assert t[3].get_internal_path() == 'd'
         assert t[3].always_build
         assert t[4].__class__.__name__ == 'Entry'
-        assert t[4].path == 'bbb'
+        assert t[4].get_internal_path() == 'bbb'
         assert t[4].always_build
         assert t[5].__class__.__name__ == 'Dir'
-        assert t[5].path == 'dir'
+        assert t[5].get_internal_path() == 'dir'
         assert t[5].always_build
         assert t[6].__class__.__name__ == 'File'
-        assert t[6].path == 'file'
+        assert t[6].get_internal_path() == 'file'
         assert t[6].always_build
 
     def test_VariantDir(self):
@@ -2811,13 +2811,13 @@ def generate(env):
         assert t.builder is not None
         assert t.builder.action.__class__.__name__ == 'CommandAction'
         assert t.builder.action.cmd_list == 'buildfoo $target $source'
-        assert 'foo1.in' in [x.path for x in t.sources]
-        assert 'foo2.in' in [x.path for x in t.sources]
+        assert 'foo1.in' in [x.get_internal_path() for x in t.sources]
+        assert 'foo2.in' in [x.get_internal_path() for x in t.sources]
 
         sub = env.fs.Dir('sub')
         t = env.Command(target='bar.out', source='sub',
                         action='buildbar $target $source')[0]
-        assert 'sub' in [x.path for x in t.sources]
+        assert 'sub' in [x.get_internal_path() for x in t.sources]
 
         def testFunc(env, target, source):
             assert str(target[0]) == 'foo.out'
@@ -2828,8 +2828,8 @@ def generate(env):
         assert t.builder is not None
         assert t.builder.action.__class__.__name__ == 'FunctionAction'
         t.build()
-        assert 'foo1.in' in [x.path for x in t.sources]
-        assert 'foo2.in' in [x.path for x in t.sources]
+        assert 'foo1.in' in [x.get_internal_path() for x in t.sources]
+        assert 'foo2.in' in [x.get_internal_path() for x in t.sources]
 
         x = []
         def test2(baz, x=x):
@@ -2846,7 +2846,7 @@ def generate(env):
                         action = 'foo',
                         X = 'xxx')[0]
         assert str(t) == 'xxx.out', str(t)
-        assert 'xxx.in' in [x.path for x in t.sources]
+        assert 'xxx.in' in [x.get_internal_path() for x in t.sources]
 
         env = self.TestEnvironment(source_scanner = 'should_not_find_this')
         t = env.Command(target='file.out', source='file.in',
@@ -2890,27 +2890,27 @@ def generate(env):
         t = env.Depends(target='EnvironmentTest.py',
                         dependency='Environment.py')[0]
         assert t.__class__.__name__ == 'Entry', t.__class__.__name__
-        assert t.path == 'EnvironmentTest.py'
+        assert t.get_internal_path() == 'EnvironmentTest.py'
         assert len(t.depends) == 1
         d = t.depends[0]
         assert d.__class__.__name__ == 'Entry', d.__class__.__name__
-        assert d.path == 'Environment.py'
+        assert d.get_internal_path() == 'Environment.py'
 
         t = env.Depends(target='${FOO}.py', dependency='${BAR}.py')[0]
         assert t.__class__.__name__ == 'File', t.__class__.__name__
-        assert t.path == 'xxx.py'
+        assert t.get_internal_path() == 'xxx.py'
         assert len(t.depends) == 1
         d = t.depends[0]
         assert d.__class__.__name__ == 'File', d.__class__.__name__
-        assert d.path == 'yyy.py'
+        assert d.get_internal_path() == 'yyy.py'
 
         t = env.Depends(target='dir1', dependency='dir2')[0]
         assert t.__class__.__name__ == 'Dir', t.__class__.__name__
-        assert t.path == 'dir1'
+        assert t.get_internal_path() == 'dir1'
         assert len(t.depends) == 1
         d = t.depends[0]
         assert d.__class__.__name__ == 'Dir', d.__class__.__name__
-        assert d.path == 'dir2'
+        assert d.get_internal_path() == 'dir2'
 
     def test_Dir(self):
         """Test the Dir() method"""
@@ -2944,19 +2944,19 @@ def generate(env):
         t = env.NoClean('p_a', 'p_${BAR}b', ['p_c', 'p_d'], 'p_$FOO')
 
         assert t[0].__class__.__name__ == 'Entry', t[0].__class__.__name__
-        assert t[0].path == 'p_a'
+        assert t[0].get_internal_path() == 'p_a'
         assert t[0].noclean
         assert t[1].__class__.__name__ == 'Dir', t[1].__class__.__name__
-        assert t[1].path == 'p_hhhb'
+        assert t[1].get_internal_path() == 'p_hhhb'
         assert t[1].noclean
         assert t[2].__class__.__name__ == 'Entry', t[2].__class__.__name__
-        assert t[2].path == 'p_c'
+        assert t[2].get_internal_path() == 'p_c'
         assert t[2].noclean
         assert t[3].__class__.__name__ == 'File', t[3].__class__.__name__
-        assert t[3].path == 'p_d'
+        assert t[3].get_internal_path() == 'p_d'
         assert t[3].noclean
         assert t[4].__class__.__name__ == 'Entry', t[4].__class__.__name__
-        assert t[4].path == 'p_ggg'
+        assert t[4].get_internal_path() == 'p_ggg'
         assert t[4].noclean
 
     def test_Dump(self):
@@ -3074,27 +3074,27 @@ def generate(env):
 
         t = env.Ignore(target='targ.py', dependency='dep.py')[0]
         assert t.__class__.__name__ == 'Entry', t.__class__.__name__
-        assert t.path == 'targ.py'
+        assert t.get_internal_path() == 'targ.py'
         assert len(t.ignore) == 1
         i = t.ignore[0]
         assert i.__class__.__name__ == 'Entry', i.__class__.__name__
-        assert i.path == 'dep.py'
+        assert i.get_internal_path() == 'dep.py'
 
         t = env.Ignore(target='$FOO$BAR', dependency='$BAR$FOO')[0]
         assert t.__class__.__name__ == 'File', t.__class__.__name__
-        assert t.path == 'yyyzzz'
+        assert t.get_internal_path() == 'yyyzzz'
         assert len(t.ignore) == 1
         i = t.ignore[0]
         assert i.__class__.__name__ == 'File', i.__class__.__name__
-        assert i.path == 'zzzyyy'
+        assert i.get_internal_path() == 'zzzyyy'
 
         t = env.Ignore(target='dir1', dependency='dir2')[0]
         assert t.__class__.__name__ == 'Dir', t.__class__.__name__
-        assert t.path == 'dir1'
+        assert t.get_internal_path() == 'dir1'
         assert len(t.ignore) == 1
         i = t.ignore[0]
         assert i.__class__.__name__ == 'Dir', i.__class__.__name__
-        assert i.path == 'dir2'
+        assert i.get_internal_path() == 'dir2'
 
     def test_Literal(self):
         """Test the Literal() method"""
@@ -3123,19 +3123,19 @@ def generate(env):
         t = env.Precious('p_a', 'p_${BAR}b', ['p_c', 'p_d'], 'p_$FOO')
 
         assert t[0].__class__.__name__ == 'Entry', t[0].__class__.__name__
-        assert t[0].path == 'p_a'
+        assert t[0].get_internal_path() == 'p_a'
         assert t[0].precious
         assert t[1].__class__.__name__ == 'Dir', t[1].__class__.__name__
-        assert t[1].path == 'p_hhhb'
+        assert t[1].get_internal_path() == 'p_hhhb'
         assert t[1].precious
         assert t[2].__class__.__name__ == 'Entry', t[2].__class__.__name__
-        assert t[2].path == 'p_c'
+        assert t[2].get_internal_path() == 'p_c'
         assert t[2].precious
         assert t[3].__class__.__name__ == 'File', t[3].__class__.__name__
-        assert t[3].path == 'p_d'
+        assert t[3].get_internal_path() == 'p_d'
         assert t[3].precious
         assert t[4].__class__.__name__ == 'Entry', t[4].__class__.__name__
-        assert t[4].path == 'p_ggg'
+        assert t[4].get_internal_path() == 'p_ggg'
         assert t[4].precious
 
     def test_Pseudo(self):
@@ -3146,19 +3146,19 @@ def generate(env):
         t = env.Pseudo('p_a', 'p_${BAR}b', ['p_c', 'p_d'], 'p_$FOO')
 
         assert t[0].__class__.__name__ == 'Entry', t[0].__class__.__name__
-        assert t[0].path == 'p_a'
+        assert t[0].get_internal_path() == 'p_a'
         assert t[0].pseudo
         assert t[1].__class__.__name__ == 'Dir', t[1].__class__.__name__
-        assert t[1].path == 'p_hhhb'
+        assert t[1].get_internal_path() == 'p_hhhb'
         assert t[1].pseudo
         assert t[2].__class__.__name__ == 'Entry', t[2].__class__.__name__
-        assert t[2].path == 'p_c'
+        assert t[2].get_internal_path() == 'p_c'
         assert t[2].pseudo
         assert t[3].__class__.__name__ == 'File', t[3].__class__.__name__
-        assert t[3].path == 'p_d'
+        assert t[3].get_internal_path() == 'p_d'
         assert t[3].pseudo
         assert t[4].__class__.__name__ == 'Entry', t[4].__class__.__name__
-        assert t[4].path == 'p_ggg'
+        assert t[4].get_internal_path() == 'p_ggg'
         assert t[4].pseudo
 
     def test_Repository(self):
@@ -3263,7 +3263,7 @@ def generate(env):
         bar = env.Object('bar.obj', 'bar.cpp')[0]
         s = env.SideEffect('mylib.pdb', ['foo.obj', 'bar.obj'])[0]
         assert s.__class__.__name__ == 'Entry', s.__class__.__name__
-        assert s.path == 'mylib.pdb'
+        assert s.get_internal_path() == 'mylib.pdb'
         assert s.side_effect
         assert foo.side_effects == [s]
         assert bar.side_effects == [s]
@@ -3272,7 +3272,7 @@ def generate(env):
         bbb = env.Object('bbb.obj', 'bbb.cpp')[0]
         s = env.SideEffect('my${LIB}.pdb', ['${FOO}.obj', '${BAR}.obj'])[0]
         assert s.__class__.__name__ == 'File', s.__class__.__name__
-        assert s.path == 'mylll.pdb'
+        assert s.get_internal_path() == 'mylll.pdb'
         assert s.side_effect
         assert fff.side_effects == [s], fff.side_effects
         assert bbb.side_effects == [s], bbb.side_effects
@@ -3281,7 +3281,7 @@ def generate(env):
         ccc = env.Object('ccc.obj', 'ccc.cpp')[0]
         s = env.SideEffect('mymmm.pdb', ['ggg.obj', 'ccc.obj'])[0]
         assert s.__class__.__name__ == 'Dir', s.__class__.__name__
-        assert s.path == 'mymmm.pdb'
+        assert s.get_internal_path() == 'mymmm.pdb'
         assert s.side_effect
         assert ggg.side_effects == [s], ggg.side_effects
         assert ccc.side_effects == [s], ccc.side_effects
@@ -3290,18 +3290,18 @@ def generate(env):
         """Test the SourceCode() method."""
         env = self.TestEnvironment(FOO='mmm', BAR='nnn')
         e = env.SourceCode('foo', None)[0]
-        assert e.path == 'foo'
+        assert e.get_internal_path() == 'foo'
         s = e.src_builder()
         assert s is None, s
 
         b = Builder()
         e = env.SourceCode(e, b)[0]
-        assert e.path == 'foo'
+        assert e.get_internal_path() == 'foo'
         s = e.src_builder()
         assert s is b, s
 
         e = env.SourceCode('$BAR$FOO', None)[0]
-        assert e.path == 'nnnmmm'
+        assert e.get_internal_path() == 'nnnmmm'
         s = e.src_builder()
         assert s is None, s
 
diff --git a/src/engine/SCons/Executor.py b/src/engine/SCons/Executor.py
index 388f8ac..98ed758 100644
--- a/src/engine/SCons/Executor.py
+++ b/src/engine/SCons/Executor.py
@@ -40,6 +40,10 @@ import SCons.Memoize
 class Batch(object):
     """Remembers exact association between targets
     and sources of executor."""
+    
+    __slots__ = ('targets',
+                 'sources')
+    
     def __init__(self, targets=[], sources=[]):
         self.targets = targets
         self.sources = sources
@@ -109,6 +113,48 @@ def rfile(node):
         return rfile()
 
 
+def execute_nothing(obj, target, kw):
+    return 0
+
+def execute_action_list(obj, target, kw):
+    """Actually execute the action list."""
+    env = obj.get_build_env()
+    kw = obj.get_kw(kw)
+    status = 0
+    for act in obj.get_action_list():
+        #args = (self.get_all_targets(), self.get_all_sources(), env)
+        args = ([], [], env)
+        status = act(*args, **kw)
+        if isinstance(status, SCons.Errors.BuildError):
+            status.executor = obj
+            raise status
+        elif status:
+            msg = "Error %s" % status
+            raise SCons.Errors.BuildError(
+                errstr=msg, 
+                node=obj.batches[0].targets,
+                executor=obj, 
+                action=act)
+    return status
+
+_do_execute_map = {0 : execute_nothing,
+                   1 : execute_action_list}
+
+
+def execute_actions_str(obj):
+    env = obj.get_build_env()
+    return "\n".join([action.genstring(obj.get_all_targets(),
+                                       obj.get_all_sources(),
+                                       env)
+                      for action in obj.get_action_list()])
+
+def execute_null_str(obj):
+    return ''
+
+_execute_str_map = {0 : execute_null_str,
+                    1 : execute_actions_str}
+
+
 class Executor(object):
     """A class for controlling instances of executing an action.
 
@@ -117,10 +163,21 @@ class Executor(object):
     and sources for later processing as needed.
     """
 
-    if SCons.Memoize.use_memoizer:
-        __metaclass__ = SCons.Memoize.Memoized_Metaclass
-
-    memoizer_counters = []
+    __slots__ = ('pre_actions',
+                 'post_actions',
+                 'env',
+                 'overridelist',
+                 'batches',
+                 'builder_kw',
+                 '_memo',
+                 'lvars',
+                 '_changed_sources_list',
+                 '_changed_targets_list',
+                 '_unchanged_sources_list',
+                 '_unchanged_targets_list',
+                 'action_list',
+                 '_do_execute',
+                 '_execute_str')
 
     def __init__(self, action, env=None, overridelist=[{}],
                  targets=[], sources=[], builder_kw={}):
@@ -135,6 +192,8 @@ class Executor(object):
         else:
             self.batches = []
         self.builder_kw = builder_kw
+        self._do_execute = 1
+        self._execute_str = 1
         self._memo = {}
 
     def get_lvars(self):
@@ -284,8 +343,7 @@ class Executor(object):
             result.extend(target.side_effects)
         return result
 
-    memoizer_counters.append(SCons.Memoize.CountValue('get_build_env'))
-
+    @SCons.Memoize.CountMethodCall
     def get_build_env(self):
         """Fetch or create the appropriate build Environment
         for this Executor.
@@ -330,36 +388,12 @@ class Executor(object):
         result['executor'] = self
         return result
 
-    def do_nothing(self, target, kw):
-        return 0
-
-    def do_execute(self, target, kw):
-        """Actually execute the action list."""
-        env = self.get_build_env()
-        kw = self.get_kw(kw)
-        status = 0
-        for act in self.get_action_list():
-            #args = (self.get_all_targets(), self.get_all_sources(), env)
-            args = ([], [], env)
-            status = act(*args, **kw)
-            if isinstance(status, SCons.Errors.BuildError):
-                status.executor = self
-                raise status
-            elif status:
-                msg = "Error %s" % status
-                raise SCons.Errors.BuildError(
-                    errstr=msg, 
-                    node=self.batches[0].targets,
-                    executor=self, 
-                    action=act)
-        return status
-
     # use extra indirection because with new-style objects (Python 2.2
     # and above) we can't override special methods, and nullify() needs
     # to be able to do this.
 
     def __call__(self, target, **kw):
-        return self.do_execute(target, kw)
+        return _do_execute_map[self._do_execute](self, target, kw)
 
     def cleanup(self):
         self._memo = {}
@@ -403,24 +437,15 @@ class Executor(object):
 
     # another extra indirection for new-style objects and nullify...
 
-    def my_str(self):
-        env = self.get_build_env()
-        return "\n".join([action.genstring(self.get_all_targets(),
-                                           self.get_all_sources(),
-                                           env)
-                          for action in self.get_action_list()])
-
-
     def __str__(self):
-        return self.my_str()
+        return _execute_str_map[self._execute_str](self)
 
     def nullify(self):
         self.cleanup()
-        self.do_execute = self.do_nothing
-        self.my_str     = lambda: ''
-
-    memoizer_counters.append(SCons.Memoize.CountValue('get_contents'))
+        self._do_execute = 0
+        self._execute_str = 0
 
+    @SCons.Memoize.CountMethodCall
     def get_contents(self):
         """Fetch the signature contents.  This is the main reason this
         class exists, so we can compute this once and cache it regardless
@@ -493,8 +518,7 @@ class Executor(object):
     def _get_unignored_sources_key(self, node, ignore=()):
         return (node,) + tuple(ignore)
 
-    memoizer_counters.append(SCons.Memoize.CountDict('get_unignored_sources', _get_unignored_sources_key))
-
+    @SCons.Memoize.CountDictCall(_get_unignored_sources_key)
     def get_unignored_sources(self, node, ignore=()):
         key = (node,) + tuple(ignore)
         try:
@@ -579,6 +603,23 @@ class Null(object):
     disassociate Builders from Nodes entirely, so we're not
     going to worry about unit tests for this--at least for now.
     """
+    
+    __slots__ = ('pre_actions',
+                 'post_actions',
+                 'env',
+                 'overridelist',
+                 'batches',
+                 'builder_kw',
+                 '_memo',
+                 'lvars',
+                 '_changed_sources_list',
+                 '_changed_targets_list',
+                 '_unchanged_sources_list',
+                 '_unchanged_targets_list',
+                 'action_list',
+                 '_do_execute',
+                 '_execute_str')
+    
     def __init__(self, *args, **kw):
         if SCons.Debug.track_instances: logInstanceCreation(self, 'Executor.Null')
         self.batches = [Batch(kw['targets'][:], [])]
diff --git a/src/engine/SCons/Memoize.py b/src/engine/SCons/Memoize.py
index e77aacf..5144f83 100644
--- a/src/engine/SCons/Memoize.py
+++ b/src/engine/SCons/Memoize.py
@@ -25,17 +25,17 @@ __revision__ = "__FILE__ __REVISION__ __DATE__ __DEVELOPER__"
 
 __doc__ = """Memoizer
 
-A metaclass implementation to count hits and misses of the computed
+A decorator-based implementation to count hits and misses of the computed
 values that various methods cache in memory.
 
 Use of this modules assumes that wrapped methods be coded to cache their
-values in a consistent way.  Here is an example of wrapping a method
-that returns a computed value, with no input parameters:
+values in a consistent way. In particular, it requires that the class uses a
+dictionary named "_memo" to store the cached values.
 
-    memoizer_counters = []                                      # Memoization
-
-    memoizer_counters.append(SCons.Memoize.CountValue('foo'))   # Memoization
+Here is an example of wrapping a method that returns a computed value,
+with no input parameters:
 
+    @SCons.Memoize.CountMethodCall
     def foo(self):
 
         try:                                                    # Memoization
@@ -55,8 +55,7 @@ based on one or more input arguments:
     def _bar_key(self, argument):                               # Memoization
         return argument                                         # Memoization
 
-    memoizer_counters.append(SCons.Memoize.CountDict('bar', _bar_key)) # Memoization
-
+    @SCons.Memoize.CountDictCall(_bar_key)
     def bar(self, argument):
 
         memo_key = argument                                     # Memoization
@@ -77,10 +76,6 @@ based on one or more input arguments:
 
         return result
 
-At one point we avoided replicating this sort of logic in all the methods
-by putting it right into this module, but we've moved away from that at
-present (see the "Historical Note," below.).
-
 Deciding what to cache is tricky, because different configurations
 can have radically different performance tradeoffs, and because the
 tradeoffs involved are often so non-obvious.  Consequently, deciding
@@ -102,51 +97,37 @@ cache return values from a method that's being called a lot:
         input arguments, you don't need to use all of the arguments
         if some of them don't affect the return values.
 
-Historical Note:  The initial Memoizer implementation actually handled
-the caching of values for the wrapped methods, based on a set of generic
-algorithms for computing hashable values based on the method's arguments.
-This collected caching logic nicely, but had two drawbacks:
-
-    Running arguments through a generic key-conversion mechanism is slower
-    (and less flexible) than just coding these things directly.  Since the
-    methods that need memoized values are generally performance-critical,
-    slowing them down in order to collect the logic isn't the right
-    tradeoff.
-
-    Use of the memoizer really obscured what was being called, because
-    all the memoized methods were wrapped with re-used generic methods.
-    This made it more difficult, for example, to use the Python profiler
-    to figure out how to optimize the underlying methods.
 """
 
-import types
-
 # A flag controlling whether or not we actually use memoization.
 use_memoizer = None
 
-CounterList = []
+# Global list of counter objects
+CounterList = {}
 
 class Counter(object):
     """
     Base class for counting memoization hits and misses.
 
-    We expect that the metaclass initialization will have filled in
-    the .name attribute that represents the name of the function
-    being counted.
+    We expect that the initialization in a matching decorator will
+    fill in the correct class name and method name that represents
+    the name of the function being counted.
     """
-    def __init__(self, method_name):
+    def __init__(self, cls_name, method_name):
         """
         """
+        self.cls_name = cls_name
         self.method_name = method_name
         self.hit = 0
         self.miss = 0
-        CounterList.append(self)
+    def key(self):
+        return self.cls_name+'.'+self.method_name
     def display(self):
         fmt = "    %7d hits %7d misses    %s()"
-        print fmt % (self.hit, self.miss, self.name)
+        print fmt % (self.hit, self.miss, self.key())
     def __cmp__(self, other):
         try:
-            return cmp(self.name, other.name)
+            return cmp(self.key(), other.key())
         except AttributeError:
             return 0
 
@@ -154,45 +135,39 @@ class CountValue(Counter):
     """
     A counter class for simple, atomic memoized values.
 
-    A CountValue object should be instantiated in a class for each of
+    A CountValue object should be instantiated in a decorator for each of
     the class's methods that memoizes its return value by simply storing
     the return value in its _memo dictionary.
-
-    We expect that the metaclass initialization will fill in the
-    .underlying_method attribute with the method that we're wrapping.
-    We then call the underlying_method method after counting whether
-    its memoized value has already been set (a hit) or not (a miss).
     """
-    def __call__(self, *args, **kw):
+    def count(self, *args, **kw):
+        """ Counts whether the memoized value has already been
+            set (a hit) or not (a miss).
+        """
         obj = args[0]
         if self.method_name in obj._memo:
             self.hit = self.hit + 1
         else:
             self.miss = self.miss + 1
-        return self.underlying_method(*args, **kw)
 
 class CountDict(Counter):
     """
     A counter class for memoized values stored in a dictionary, with
     keys based on the method's input arguments.
 
-    A CountDict object is instantiated in a class for each of the
+    A CountDict object is instantiated in a decorator for each of the
     class's methods that memoizes its return value in a dictionary,
     indexed by some key that can be computed from one or more of
     its input arguments.
-
-    We expect that the metaclass initialization will fill in the
-    .underlying_method attribute with the method that we're wrapping.
-    We then call the underlying_method method after counting whether the
-    computed key value is already present in the memoization dictionary
-    (a hit) or not (a miss).
     """
-    def __init__(self, method_name, keymaker):
+    def __init__(self, cls_name, method_name, keymaker):
         """
         """
-        Counter.__init__(self, method_name)
+        Counter.__init__(self, cls_name, method_name)
         self.keymaker = keymaker
-    def __call__(self, *args, **kw):
+    def count(self, *args, **kw):
+        """ Counts whether the computed key value is already present
+           in the memoization dictionary (a hit) or not (a miss).
+        """
         obj = args[0]
         try:
             memo_dict = obj._memo[self.method_name]
@@ -204,39 +179,65 @@ class CountDict(Counter):
                 self.hit = self.hit + 1
             else:
                 self.miss = self.miss + 1
-        return self.underlying_method(*args, **kw)
-
-class Memoizer(object):
-    """Object which performs caching of method calls for its 'primary'
-    instance."""
-
-    def __init__(self):
-        pass
 
 def Dump(title=None):
+    """ Dump the hit/miss count for all the counters
+        collected so far.
+    """
     if title:
         print title
-    CounterList.sort()
-    for counter in CounterList:
-        counter.display()
-
-class Memoized_Metaclass(type):
-    def __init__(cls, name, bases, cls_dict):
-        super(Memoized_Metaclass, cls).__init__(name, bases, cls_dict)
-
-        for counter in cls_dict.get('memoizer_counters', []):
-            method_name = counter.method_name
-
-            counter.name = cls.__name__ + '.' + method_name
-            counter.underlying_method = cls_dict[method_name]
-
-            replacement_method = types.MethodType(counter, None, cls)
-            setattr(cls, method_name, replacement_method)
+    for counter in sorted(CounterList):
+        CounterList[counter].display()
 
 def EnableMemoization():
     global use_memoizer
     use_memoizer = 1
 
+def CountMethodCall(fn):
+    """ Decorator for counting memoizer hits/misses while retrieving
+        a simple value in a class method. It wraps the given method
+        fn and uses a CountValue object to keep track of the
+        caching statistics.
+        Wrapping gets enabled by calling EnableMemoization().
+    """
+    if use_memoizer:
+        def wrapper(self, *args, **kwargs):
+            global CounterList
+            key = self.__class__.__name__+'.'+fn.__name__
+            if key not in CounterList:
+                CounterList[key] = CountValue(self.__class__.__name__, fn.__name__)
+            CounterList[key].count(self, *args, **kwargs)
+            return fn(self, *args, **kwargs)
+        wrapper.__name__= fn.__name__
+        return wrapper
+    else:
+        return fn
+
+def CountDictCall(keyfunc):
+    """ Decorator for counting memoizer hits/misses while accessing
+        dictionary values with a key-generating function. Like
+        CountMethodCall above, it wraps the given method
+        fn and uses a CountDict object to keep track of the
+        caching statistics. The dict-key function keyfunc has to
+        get passed in the decorator call and gets stored in the
+        CountDict instance.
+        Wrapping gets enabled by calling EnableMemoization().
+    """
+    def decorator(fn):
+        if use_memoizer:
+            def wrapper(self, *args, **kwargs):
+                global CounterList
+                key = self.__class__.__name__+'.'+fn.__name__
+                if key not in CounterList:
+                    CounterList[key] = CountDict(self.__class__.__name__, fn.__name__, keyfunc)
+                CounterList[key].count(self, *args, **kwargs)
+                return fn(self, *args, **kwargs)
+            wrapper.__name__= fn.__name__
+            return wrapper
+        else:
+            return fn
+    return decorator
+
 # Local Variables:
 # tab-width:4
 # indent-tabs-mode:nil
diff --git a/src/engine/SCons/MemoizeTests.py b/src/engine/SCons/MemoizeTests.py
index 3606d57..77ff6bc 100644
--- a/src/engine/SCons/MemoizeTests.py
+++ b/src/engine/SCons/MemoizeTests.py
@@ -30,22 +30,18 @@ import TestUnit
 
 import SCons.Memoize
 
-
+# Enable memoization counting
+SCons.Memoize.EnableMemoization()
 
 class FakeObject(object):
 
-    __metaclass__ = SCons.Memoize.Memoized_Metaclass
-
-    memoizer_counters = []
-
     def __init__(self):
         self._memo = {}
 
     def _dict_key(self, argument):
         return argument
 
-    memoizer_counters.append(SCons.Memoize.CountDict('dict', _dict_key))
-
+    @SCons.Memoize.CountDictCall(_dict_key)
     def dict(self, argument):
 
         memo_key = argument
@@ -66,8 +62,7 @@ class FakeObject(object):
 
         return result
 
-    memoizer_counters.append(SCons.Memoize.CountValue('value'))
-
+    @SCons.Memoize.CountMethodCall
     def value(self):
 
         try:
@@ -82,10 +77,7 @@ class FakeObject(object):
         return result
 
     def get_memoizer_counter(self, name):
-        for mc in self.memoizer_counters:
-            if mc.method_name == name:
-                return mc
-        return  None
+        return SCons.Memoize.CounterList.get(self.__class__.__name__+'.'+name, None)
 
 class Returner(object):
     def __init__(self, result):
diff --git a/src/engine/SCons/Node/Alias.py b/src/engine/SCons/Node/Alias.py
index f817356..a035816 100644
--- a/src/engine/SCons/Node/Alias.py
+++ b/src/engine/SCons/Node/Alias.py
@@ -56,13 +56,47 @@ class AliasNameSpace(collections.UserDict):
             return None
 
 class AliasNodeInfo(SCons.Node.NodeInfoBase):
-    current_version_id = 1
+    __slots__ = ('csig',)
+    current_version_id = 2
     field_list = ['csig']
     def str_to_node(self, s):
         return default_ans.Alias(s)
 
+    def __getstate__(self):
+        """
+        Return all fields that shall be pickled. Walk the slots in the class
+        hierarchy and add those to the state dictionary. If a '__dict__' slot is
+        available, copy all entries to the dictionary. Also include the version
+        id, which is fixed for all instances of a class.
+        """
+        state = getattr(self, '__dict__', {}).copy()
+        for obj in type(self).mro():
+            for name in getattr(obj,'__slots__',()):
+                if hasattr(self, name):
+                    state[name] = getattr(self, name)
+
+        state['_version_id'] = self.current_version_id
+        try:
+            del state['__weakref__']
+        except KeyError:
+            pass
+
+        return state
+
+    def __setstate__(self, state):
+        """
+        Restore the attributes from a pickled state.
+        """
+        # TODO check or discard version
+        del state['_version_id']
+        for key, value in state.items():
+            if key not in ('__weakref__',):
+                setattr(self, key, value)
+          
+
 class AliasBuildInfo(SCons.Node.BuildInfoBase):
-    current_version_id = 1
+    __slots__ = ()
+    current_version_id = 2
 
 class Alias(SCons.Node.Node):
 
@@ -72,7 +106,9 @@ class Alias(SCons.Node.Node):
     def __init__(self, name):
         SCons.Node.Node.__init__(self)
         self.name = name
-
+        self.changed_since_last_build = 1
+        self.store_info = 0
+        
     def str_for_display(self):
         return '"' + self.__str__() + '"'
 
@@ -105,13 +141,6 @@ class Alias(SCons.Node.Node):
     #
     #
 
-    def changed_since_last_build(self, target, prev_ni):
-        cur_csig = self.get_csig()
-        try:
-            return cur_csig != prev_ni.csig
-        except AttributeError:
-            return 1
-
     def build(self):
         """A "builder" for aliases."""
         pass
diff --git a/src/engine/SCons/Node/AliasTests.py b/src/engine/SCons/Node/AliasTests.py
index 2d11bdf..8e31875 100644
--- a/src/engine/SCons/Node/AliasTests.py
+++ b/src/engine/SCons/Node/AliasTests.py
@@ -103,14 +103,14 @@ class AliasNodeInfoTestCase(unittest.TestCase):
         """Test AliasNodeInfo initialization"""
         ans = SCons.Node.Alias.AliasNameSpace()
         aaa = ans.Alias('aaa')
-        ni = SCons.Node.Alias.AliasNodeInfo(aaa)
+        ni = SCons.Node.Alias.AliasNodeInfo()
 
 class AliasBuildInfoTestCase(unittest.TestCase):
     def test___init__(self):
         """Test AliasBuildInfo initialization"""
         ans = SCons.Node.Alias.AliasNameSpace()
         aaa = ans.Alias('aaa')
-        bi = SCons.Node.Alias.AliasBuildInfo(aaa)
+        bi = SCons.Node.Alias.AliasBuildInfo()
 
 if __name__ == "__main__":
     suite = unittest.TestSuite()
diff --git a/src/engine/SCons/Node/FS.py b/src/engine/SCons/Node/FS.py
index 4db1cb3..2402fac 100644
--- a/src/engine/SCons/Node/FS.py
+++ b/src/engine/SCons/Node/FS.py
@@ -56,10 +56,23 @@ import SCons.Warnings
 
 from SCons.Debug import Trace
 
-do_store_info = True
 print_duplicate = 0
 
 
+def sconsign_none(node):
+    raise NotImplementedError
+
+def sconsign_dir(node):
+    """Return the .sconsign file info for this directory,
+    creating it first if necessary."""
+    if not node._sconsign:
+        import SCons.SConsign
+        node._sconsign = SCons.SConsign.ForDirectory(node)
+    return node._sconsign
+
+_sconsign_map = {0 : sconsign_none,
+                 1 : sconsign_dir}
+
 class EntryProxyAttributeError(AttributeError):
     """
     An AttributeError subclass for recording and displaying the name
@@ -268,8 +281,8 @@ def LinkFunc(target, source, env):
     # who want to move their soft-linked src-trees around. Those
     # people should use the 'hard-copy' mode, softlinks cannot be
     # used for that; at least I have no idea how ...
-    src = source[0].abspath
-    dest = target[0].abspath
+    src = source[0].get_abspath()
+    dest = target[0].get_abspath()
     dir, file = os.path.split(dest)
     if dir and not target[0].fs.isdir(dir):
         os.makedirs(dir)
@@ -302,7 +315,7 @@ LocalCopy = SCons.Action.Action(LinkFunc, LocalString)
 
 def UnlinkFunc(target, source, env):
     t = target[0]
-    t.fs.unlink(t.abspath)
+    t.fs.unlink(t.get_abspath())
     return 0
 
 Unlink = SCons.Action.Action(UnlinkFunc, None)
@@ -310,7 +323,7 @@ Unlink = SCons.Action.Action(UnlinkFunc, None)
 def MkdirFunc(target, source, env):
     t = target[0]
     if not t.exists():
-        t.fs.mkdir(t.abspath)
+        t.fs.mkdir(t.get_abspath())
     return 0
 
 Mkdir = SCons.Action.Action(MkdirFunc, None, presub=None)
@@ -403,7 +416,7 @@ def do_diskcheck_match(node, predicate, errorfmt):
     except (AttributeError, KeyError):
         pass
     if result:
-        raise TypeError(errorfmt % node.abspath)
+        raise TypeError(errorfmt % node.get_abspath())
 
 def ignore_diskcheck_match(node, predicate, errorfmt):
     pass
@@ -573,7 +586,20 @@ class Base(SCons.Node.Node):
     object identity comparisons.
     """
 
-    memoizer_counters = []
+    __slots__ = ['name',
+                 'fs',
+                 'abspath',
+                 'labspath',
+                 'path',
+                 'tpath',
+                 'path_elements',
+                 'dir',
+                 'cwd',
+                 'duplicate',
+                 '_local',
+                 'sbuilder',
+                 '_proxy',
+                 '_func_sconsign']
 
     def __init__(self, name, directory, fs):
         """Initialize a generic Node.FS.Base object.
@@ -591,27 +617,26 @@ class Base(SCons.Node.Node):
         #: Filename with extension as it was specified when the object was
         #: created; to obtain filesystem path, use Python str() function
         self.name = SCons.Util.silent_intern(name)
-        #: Cached filename extension
-        self.suffix = SCons.Util.silent_intern(SCons.Util.splitext(name)[1])
         self.fs = fs #: Reference to parent Node.FS object
 
         assert directory, "A directory must be provided"
 
-        self.abspath = SCons.Util.silent_intern(directory.entry_abspath(name))
-        self.labspath = SCons.Util.silent_intern(directory.entry_labspath(name))
-        if directory.path == '.':
-            self.path = SCons.Util.silent_intern(name)
-        else:
-            self.path = SCons.Util.silent_intern(directory.entry_path(name))
-        if directory.tpath == '.':
-            self.tpath = SCons.Util.silent_intern(name)
-        else:
-            self.tpath = SCons.Util.silent_intern(directory.entry_tpath(name))
-        self.path_elements = directory.path_elements + [self]
+        self.abspath = None
+        self.labspath = None
+        self.path = None
+        self.tpath = None
+        self.path_elements = None
 
         self.dir = directory
         self.cwd = None # will hold the SConscript directory for target nodes
         self.duplicate = directory.duplicate
+        self.changed_since_last_build = 2
+        self._func_sconsign = 0
+        self._func_exists = 2
+        self._func_rexists = 2
+        self._func_get_contents = 0
+        self._func_target_from_source = 1
+        self.store_info = 1
 
     def str_for_display(self):
         return '"' + self.__str__() + '"'
@@ -624,13 +649,13 @@ class Base(SCons.Node.Node):
         if isinstance(self, klass) or klass is Entry:
             return
         raise TypeError("Tried to lookup %s '%s' as a %s." %\
-              (self.__class__.__name__, self.path, klass.__name__))
+              (self.__class__.__name__, self.get_internal_path(), klass.__name__))
 
     def get_dir(self):
         return self.dir
 
     def get_suffix(self):
-        return self.suffix
+        return SCons.Util.splitext(self.name)[1]
 
     def rfile(self):
         return self
@@ -643,8 +668,7 @@ class Base(SCons.Node.Node):
             return self._save_str()
         return self._get_str()
 
-    memoizer_counters.append(SCons.Memoize.CountValue('_save_str'))
-
+    @SCons.Memoize.CountMethodCall
     def _save_str(self):
         try:
             return self._memo['_save_str']
@@ -681,21 +705,20 @@ class Base(SCons.Node.Node):
 
     rstr = __str__
 
-    memoizer_counters.append(SCons.Memoize.CountValue('stat'))
-
+    @SCons.Memoize.CountMethodCall
     def stat(self):
         try: return self._memo['stat']
         except KeyError: pass
-        try: result = self.fs.stat(self.abspath)
+        try: result = self.fs.stat(self.get_abspath())
         except os.error: result = None
         self._memo['stat'] = result
         return result
 
     def exists(self):
-        return self.stat() is not None
+        return SCons.Node._exists_map[self._func_exists](self)
 
     def rexists(self):
-        return self.rfile().exists()
+        return SCons.Node._rexists_map[self._func_rexists](self)
 
     def getmtime(self):
         st = self.stat()
@@ -717,7 +740,7 @@ class Base(SCons.Node.Node):
 
     if hasattr(os, 'symlink'):
         def islink(self):
-            try: st = self.fs.lstat(self.abspath)
+            try: st = self.fs.lstat(self.get_abspath())
             except os.error: return 0
             return stat.S_ISLNK(st[stat.ST_MODE])
     else:
@@ -752,7 +775,7 @@ class Base(SCons.Node.Node):
             dir = self.fs.getcwd()
         if self == dir:
             return '.'
-        path_elems = self.path_elements
+        path_elems = self.get_path_elements()
         pathname = ''
         try: i = path_elems.index(dir)
         except ValueError: 
@@ -785,7 +808,26 @@ class Base(SCons.Node.Node):
 
     def get_abspath(self):
         """Get the absolute path of the file."""
-        return self.abspath
+        return self.dir.entry_abspath(self.name)
+
+    def get_labspath(self):
+        """Get the absolute path of the file."""
+        return self.dir.entry_labspath(self.name)
+
+    def get_internal_path(self):
+        if self.dir.path == '.':
+            return self.name
+        else:
+            return self.dir.entry_path(self.name)
+        
+    def get_tpath(self):
+        if self.dir.tpath == '.':
+            return self.name
+        else:
+            return self.dir.entry_tpath(self.name)
+        
+    def get_path_elements(self):
+        return self.dir.path_elements + [self]
 
     def for_signature(self):
         # Return just our name.  Even an absolute path would not work,
@@ -811,13 +853,12 @@ class Base(SCons.Node.Node):
         files that need different behavior.  See Tool/swig.py for
         an example.
         """
-        return self.dir.Entry(prefix + splitext(self.name)[0] + suffix)
+        return SCons.Node._target_from_source_map[self._func_target_from_source](self, prefix, suffix, splitext)
 
     def _Rfindalldirs_key(self, pathlist):
         return pathlist
 
-    memoizer_counters.append(SCons.Memoize.CountDict('Rfindalldirs', _Rfindalldirs_key))
-
+    @SCons.Memoize.CountDictCall(_Rfindalldirs_key)
     def Rfindalldirs(self, pathlist):
         """
         Return all of the directories for a given path list, including
@@ -856,8 +897,7 @@ class Base(SCons.Node.Node):
         cwd = self.cwd or self.fs._cwd
         return cwd.Rfindalldirs(pathlist)
 
-    memoizer_counters.append(SCons.Memoize.CountValue('rentry'))
-
+    @SCons.Memoize.CountMethodCall
     def rentry(self):
         try:
             return self._memo['rentry']
@@ -878,7 +918,7 @@ class Base(SCons.Node.Node):
 
     def _glob1(self, pattern, ondisk=True, source=False, strings=False):
         return []
-
+    
 class Entry(Base):
     """This is the class for generic Node.FS entries--that is, things
     that could be a File or a Dir, but we're just not sure yet.
@@ -887,6 +927,28 @@ class Entry(Base):
     time comes, and then call the same-named method in the transformed
     class."""
 
+    __slots__ = ['scanner_paths',
+                 'cachedir_csig',
+                 'cachesig',
+                 'repositories',
+                 'srcdir',
+                 'entries',
+                 'searched',
+                 '_sconsign',
+                 'variant_dirs',
+                 'root',
+                 'dirname',
+                 'on_disk_entries',
+                 'sccs_dir',
+                 'rcs_dir',
+                 'released_target_info',
+                 'contentsig']
+
+    def __init__(self, name, directory, fs):
+        Base.__init__(self, name, directory, fs)
+        self._func_exists = 3
+        self._func_get_contents = 1 
+
     def diskcheck_match(self):
         pass
 
@@ -917,7 +979,7 @@ class Entry(Base):
                 self.__class__ = Dir
                 self._morph()
             elif must_exist:
-                msg = "No such file or directory: '%s'" % self.abspath
+                msg = "No such file or directory: '%s'" % self.get_abspath()
                 raise SCons.Errors.UserError(msg)
             else:
                 self.__class__ = File
@@ -939,17 +1001,7 @@ class Entry(Base):
     def get_contents(self):
         """Fetch the contents of the entry.  Returns the exact binary
         contents of the file."""
-        try:
-            self = self.disambiguate(must_exist=1)
-        except SCons.Errors.UserError:
-            # There was nothing on disk with which to disambiguate
-            # this entry.  Leave it as an Entry, but return a null
-            # string so calls to get_contents() in emitters and the
-            # like (e.g. in qt.py) don't have to disambiguate by hand
-            # or catch the exception.
-            return ''
-        else:
-            return self.get_contents()
+        return SCons.Node._get_contents_map[self._func_get_contents](self)
 
     def get_text_contents(self):
         """Fetch the decoded text contents of a Unicode encoded Entry.
@@ -989,10 +1041,7 @@ class Entry(Base):
     # to make various tests pass.
 
     def exists(self):
-        """Return if the Entry exists.  Check the file system to see
-        what we should turn into first.  Assume a file if there's no
-        directory."""
-        return self.disambiguate().exists()
+        return SCons.Node._exists_map[self._func_exists](self)
 
     def rel_path(self, other):
         d = self.disambiguate()
@@ -1003,9 +1052,6 @@ class Entry(Base):
     def new_ninfo(self):
         return self.disambiguate().new_ninfo()
 
-    def changed_since_last_build(self, target, prev_ni):
-        return self.disambiguate().changed_since_last_build(target, prev_ni)
-
     def _glob1(self, pattern, ondisk=True, source=False, strings=False):
         return self.disambiguate()._glob1(pattern, ondisk, source, strings)
 
@@ -1019,9 +1065,6 @@ _classEntry = Entry
 
 class LocalFS(object):
 
-    if SCons.Memoize.use_memoizer:
-        __metaclass__ = SCons.Memoize.Memoized_Metaclass
-
     # This class implements an abstraction layer for operations involving
     # a local file system.  Essentially, this wraps any function in
     # the os, os.path or shutil modules that we use to actually go do
@@ -1101,8 +1144,6 @@ class LocalFS(object):
 
 class FS(LocalFS):
 
-    memoizer_counters = []
-
     def __init__(self, path = None):
         """Initialize the Node.FS subsystem.
 
@@ -1160,7 +1201,7 @@ class FS(LocalFS):
             if dir is not None:
                 self._cwd = dir
                 if change_os_dir:
-                    os.chdir(dir.abspath)
+                    os.chdir(dir.get_abspath())
         except OSError:
             self._cwd = curr
             raise
@@ -1249,9 +1290,9 @@ class FS(LocalFS):
             
             # The path is relative to the top-level SCons directory.
             if p in ('', '.'):
-                p = directory.labspath
+                p = directory.get_labspath()
             else:
-                p = directory.labspath + '/' + p
+                p = directory.get_labspath() + '/' + p
         else:
             if do_splitdrive:
                 drive, p = _my_splitdrive(p)
@@ -1285,9 +1326,9 @@ class FS(LocalFS):
                     directory = self._cwd
 
                 if p in ('', '.'):
-                    p = directory.labspath
+                    p = directory.get_labspath()
                 else:
-                    p = directory.labspath + '/' + p
+                    p = directory.get_labspath() + '/' + p
 
                 if drive:
                     root = self.get_root(drive)
@@ -1412,8 +1453,9 @@ class FS(LocalFS):
         return cwd.glob(pathname, ondisk, source, strings)
 
 class DirNodeInfo(SCons.Node.NodeInfoBase):
+    __slots__ = ()
     # This should get reset by the FS initialization.
-    current_version_id = 1
+    current_version_id = 2
 
     fs = None
 
@@ -1425,11 +1467,12 @@ class DirNodeInfo(SCons.Node.NodeInfoBase):
             if drive:
                 root = self.fs.get_root(drive)
         if not os.path.isabs(s):
-            s = top.labspath + '/' + s
+            s = top.get_labspath() + '/' + s
         return root._lookup_abs(s, Entry)
 
 class DirBuildInfo(SCons.Node.BuildInfoBase):
-    current_version_id = 1
+    __slots__ = ()
+    current_version_id = 2
 
 glob_magic_check = re.compile('[*?[]')
 
@@ -1440,7 +1483,22 @@ class Dir(Base):
     """A class for directories in a file system.
     """
 
-    memoizer_counters = []
+    __slots__ = ['scanner_paths',
+                 'cachedir_csig',
+                 'cachesig',
+                 'repositories',
+                 'srcdir',
+                 'entries',
+                 'searched',
+                 '_sconsign',
+                 'variant_dirs',
+                 'root',
+                 'dirname',
+                 'on_disk_entries',
+                 'sccs_dir',
+                 'rcs_dir',
+                 'released_target_info',
+                 'contentsig']
 
     NodeInfo = DirNodeInfo
     BuildInfo = DirBuildInfo
@@ -1470,6 +1528,22 @@ class Dir(Base):
         self._sconsign = None
         self.variant_dirs = []
         self.root = self.dir.root
+        self.changed_since_last_build = 3
+        self._func_sconsign = 1
+        self._func_exists = 2
+        self._func_get_contents = 2
+        
+        self.abspath = SCons.Util.silent_intern(self.dir.entry_abspath(self.name))
+        self.labspath = SCons.Util.silent_intern(self.dir.entry_labspath(self.name))
+        if self.dir.path == '.':
+            self.path = SCons.Util.silent_intern(self.name)
+        else:
+            self.path = SCons.Util.silent_intern(self.dir.entry_path(self.name))
+        if self.dir.tpath == '.':
+            self.tpath = SCons.Util.silent_intern(self.name)
+        else:
+            self.tpath = SCons.Util.silent_intern(self.dir.entry_tpath(self.name))
+        self.path_elements = self.dir.path_elements + [self]
 
         # For directories, we make a difference between the directory
         # 'name' and the directory 'dirname'. The 'name' attribute is
@@ -1562,8 +1636,7 @@ class Dir(Base):
             return self.srcdir.get_all_rdirs() + self.repositories
         return self.repositories
 
-    memoizer_counters.append(SCons.Memoize.CountValue('get_all_rdirs'))
-
+    @SCons.Memoize.CountMethodCall
     def get_all_rdirs(self):
         try:
             return list(self._memo['get_all_rdirs'])
@@ -1598,8 +1671,7 @@ class Dir(Base):
     def _rel_path_key(self, other):
         return str(other)
 
-    memoizer_counters.append(SCons.Memoize.CountDict('rel_path', _rel_path_key))
-
+    @SCons.Memoize.CountDictCall(_rel_path_key)
     def rel_path(self, other):
         """Return a path to "other" relative to this directory.
         """
@@ -1753,10 +1825,7 @@ class Dir(Base):
     def get_contents(self):
         """Return content signatures and names of all our children
         separated by new-lines. Ensure that the nodes are sorted."""
-        contents = []
-        for node in sorted(self.children(), key=lambda t: t.name):
-            contents.append('%s %s\n' % (node.get_csig(), node.name))
-        return ''.join(contents)
+        return SCons.Node._get_contents_map[self._func_get_contents](self)
 
     def get_csig(self):
         """Compute the content signature for Directory nodes. In
@@ -1770,8 +1839,6 @@ class Dir(Base):
     def do_duplicate(self, src):
         pass
 
-    changed_since_last_build = SCons.Node.Node.state_has_changed
-
     def is_up_to_date(self):
         """If any child is not up-to-date, then this directory isn't,
         either."""
@@ -1795,12 +1862,8 @@ class Dir(Base):
         return self
 
     def sconsign(self):
-        """Return the .sconsign file info for this directory,
-        creating it first if necessary."""
-        if not self._sconsign:
-            import SCons.SConsign
-            self._sconsign = SCons.SConsign.ForDirectory(self)
-        return self._sconsign
+        """Return the .sconsign file info for this directory. """
+        return _sconsign_map[self._func_sconsign](self)
 
     def srcnode(self):
         """Dir has a special need for srcnode()...if we
@@ -1817,6 +1880,23 @@ class Dir(Base):
                 stamp = kid.get_timestamp()
         return stamp
 
+    def get_abspath(self):
+        """Get the absolute path of the file."""
+        return self.abspath
+
+    def get_labspath(self):
+        """Get the absolute path of the file."""
+        return self.labspath
+
+    def get_internal_path(self):
+        return self.path
+        
+    def get_tpath(self):
+        return self.tpath
+        
+    def get_path_elements(self):
+        return self.path_elements
+
     def entry_abspath(self, name):
         return self.abspath + OS_SEP + name
 
@@ -1887,8 +1967,7 @@ class Dir(Base):
                         break
         return rentry_exists
 
-    memoizer_counters.append(SCons.Memoize.CountValue('srcdir_list'))
-
+    @SCons.Memoize.CountMethodCall
     def srcdir_list(self):
         try:
             return self._memo['srcdir_list']
@@ -1929,8 +2008,7 @@ class Dir(Base):
     def _srcdir_find_file_key(self, filename):
         return filename
 
-    memoizer_counters.append(SCons.Memoize.CountDict('srcdir_find_file', _srcdir_find_file_key))
-
+    @SCons.Memoize.CountDictCall(_srcdir_find_file_key)
     def srcdir_find_file(self, filename):
         try:
             memo_dict = self._memo['srcdir_find_file']
@@ -2066,8 +2144,9 @@ class Dir(Base):
             if strings:
                 r = [os.path.join(str(dir), x) for x in r]
             result.extend(r)
-        return sorted(result, key=lambda a: str(a))
 
+        return sorted(result, key=lambda a: str(a))
+        
     def _glob1(self, pattern, ondisk=True, source=False, strings=False):
         """
         Globs for and returns a list of entry names matching a single
@@ -2146,18 +2225,12 @@ class RootDir(Dir):
     add a separator when creating the path names of entries within
     this directory.
     """
+    
+    __slots__ = ['_lookupDict']
+    
     def __init__(self, drive, fs):
         if SCons.Debug.track_instances: logInstanceCreation(self, 'Node.FS.RootDir')
-        # We're going to be our own parent directory (".." entry and .dir
-        # attribute) so we have to set up some values so Base.__init__()
-        # won't gag won't it calls some of our methods.
-        self.abspath = ''
-        self.labspath = ''
-        self.path = ''
-        self.tpath = ''
-        self.path_elements = []
-        self.duplicate = 0
-        self.root = self
+        SCons.Node.Node.__init__(self)
 
         # Handle all the types of drives:
         if drive == '':
@@ -2173,7 +2246,16 @@ class RootDir(Dir):
             name = drive
             dirname = drive + OS_SEP
 
-        Base.__init__(self, name, self, fs)
+        #: Filename with extension as it was specified when the object was
+        #: created; to obtain filesystem path, use Python str() function
+        self.name = SCons.Util.silent_intern(name)
+        self.fs = fs #: Reference to parent Node.FS object
+
+        self.path_elements = [self]
+        self.dir = self
+        self._func_rexists = 2
+        self._func_target_from_source = 1
+        self.store_info = 1
 
         # Now set our paths to what we really want them to be. The
         # name should already contain any necessary separators, such
@@ -2184,22 +2266,65 @@ class RootDir(Dir):
         self.labspath = ''
         self.path = dirname
         self.tpath = dirname
-        self._morph()
-
-        # Must be reset after Dir._morph() is invoked...
         self.dirname = dirname
 
+        self._morph()
+
+        self.duplicate = 0
         self._lookupDict = {}
 
         self._lookupDict[''] = self
         self._lookupDict['/'] = self
-
+        self.root = self
         # The // entry is necessary because os.path.normpath()
         # preserves double slashes at the beginning of a path on Posix
         # platforms.
         if not has_unc:
             self._lookupDict['//'] = self
 
+    def _morph(self):
+        """Turn a file system Node (either a freshly initialized directory
+        object or a separate Entry object) into a proper directory object.
+
+        Set up this directory's entries and hook it into the file
+        system tree.  Specify that directories (this Node) don't use
+        signatures for calculating whether they're current.
+        """
+
+        self.repositories = []
+        self.srcdir = None
+
+        self.entries = {}
+        self.entries['.'] = self
+        self.entries['..'] = self.dir
+        self.cwd = self
+        self.searched = 0
+        self._sconsign = None
+        self.variant_dirs = []
+        self.changed_since_last_build = 3
+        self._func_sconsign = 1
+        self._func_exists = 2
+        self._func_get_contents = 2
+        
+        # Don't just reset the executor, replace its action list,
+        # because it might have some pre-or post-actions that need to
+        # be preserved.
+        #
+        # But don't reset the executor if there is a non-null executor
+        # attached already. The existing executor might have other
+        # targets, in which case replacing the action list with a
+        # Mkdir action is a big mistake.
+        if not hasattr(self, 'executor'):
+            self.builder = get_MkdirBuilder()
+            self.get_executor().set_action_list(self.builder.action)
+        else:
+            # Prepend MkdirBuilder action to existing action list
+            l = self.get_executor().action_list
+            a = get_MkdirBuilder().action
+            l.insert(0, a) 
+            self.get_executor().set_action_list(l)
+      
+
     def must_be_same(self, klass):
         if klass is Dir:
             return
@@ -2278,7 +2403,8 @@ class RootDir(Dir):
         return _null
 
 class FileNodeInfo(SCons.Node.NodeInfoBase):
-    current_version_id = 1
+    __slots__ = ('csig', 'timestamp', 'size')
+    current_version_id = 2
 
     field_list = ['csig', 'timestamp', 'size']
 
@@ -2293,11 +2419,43 @@ class FileNodeInfo(SCons.Node.NodeInfoBase):
             if drive:
                 root = self.fs.get_root(drive)
         if not os.path.isabs(s):
-            s = top.labspath + '/' + s
+            s = top.get_labspath() + '/' + s
         return root._lookup_abs(s, Entry)
 
+    def __getstate__(self):
+        """
+        Return all fields that shall be pickled. Walk the slots in the class
+        hierarchy and add those to the state dictionary. If a '__dict__' slot is
+        available, copy all entries to the dictionary. Also include the version
+        id, which is fixed for all instances of a class.
+        """
+        state = getattr(self, '__dict__', {}).copy()
+        for obj in type(self).mro():
+            for name in getattr(obj,'__slots__',()):
+                if hasattr(self, name):
+                    state[name] = getattr(self, name)
+
+        state['_version_id'] = self.current_version_id
+        try:
+            del state['__weakref__']
+        except KeyError:
+            pass
+
+        return state
+
+    def __setstate__(self, state):
+        """
+        Restore the attributes from a pickled state.
+        """
+        # TODO check or discard version
+        del state['_version_id']
+        for key, value in state.items():
+            if key not in ('__weakref__',):
+                setattr(self, key, value)
+
 class FileBuildInfo(SCons.Node.BuildInfoBase):
-    current_version_id = 1
+    __slots__ = ()
+    current_version_id = 2
 
     def convert_to_sconsign(self):
         """
@@ -2312,7 +2470,7 @@ class FileBuildInfo(SCons.Node.BuildInfoBase):
         else:
             def node_to_str(n):
                 try:
-                    s = n.path
+                    s = n.get_internal_path()
                 except AttributeError:
                     s = str(n)
                 else:
@@ -2353,6 +2511,8 @@ class FileBuildInfo(SCons.Node.BuildInfoBase):
                 nodeinfos = getattr(self, sattr)
             except AttributeError:
                 continue
+            if strings is None or nodeinfos is None:
+                continue
             nodes = []
             for s, ni in zip(strings, nodeinfos):
                 if not isinstance(s, SCons.Node.Node):
@@ -2366,6 +2526,8 @@ class FileBuildInfo(SCons.Node.BuildInfoBase):
         for bkid, bkidsig in zip(bkids, bkidsigs):
             result.append(str(bkid) + ': ' +
                           ' '.join(bkidsig.format(names=names)))
+        if not hasattr(self,'bact'):
+            self.bact = "none"
         result.append('%s [%s]' % (self.bactsig, self.bact))
         return '\n'.join(result)
 
@@ -2373,7 +2535,22 @@ class File(Base):
     """A class for files in a file system.
     """
 
-    memoizer_counters = []
+    __slots__ = ['scanner_paths',
+                 'cachedir_csig',
+                 'cachesig',
+                 'repositories',
+                 'srcdir',
+                 'entries',
+                 'searched',
+                 '_sconsign',
+                 'variant_dirs',
+                 'root',
+                 'dirname',
+                 'on_disk_entries',
+                 'sccs_dir',
+                 'rcs_dir',
+                 'released_target_info',
+                 'contentsig']
 
     NodeInfo = FileNodeInfo
     BuildInfo = FileBuildInfo
@@ -2424,6 +2601,14 @@ class File(Base):
         if not hasattr(self, 'released_target_info'):
             self.released_target_info = False
 
+        self.store_info = 1
+        self._func_exists = 4
+        self._func_get_contents = 3
+        
+        # Initialize this Node's decider function to decide_source() because
+        # every file is a source file until it has a Builder attached...
+        self.changed_since_last_build = 4
+        
         # If there was already a Builder set on this entry, then
         # we need to make sure we call the target-decider function,
         # not the source-decider.  Reaching in and doing this by hand
@@ -2435,22 +2620,13 @@ class File(Base):
         # not clear right now how to fix that, stick with what works
         # until it becomes clear...
         if self.has_builder():
-            self.changed_since_last_build = self.decide_target
+            self.changed_since_last_build = 5
 
     def scanner_key(self):
         return self.get_suffix()
 
     def get_contents(self):
-        if not self.rexists():
-            return ''
-        fname = self.rfile().abspath
-        try:
-            contents = open(fname, "rb").read()
-        except EnvironmentError, e:
-            if not e.filename:
-                e.filename = fname
-            raise
-        return contents
+        return SCons.Node._get_contents_map[self._func_get_contents](self)
 
     # This attempts to figure out what the encoding of the text is
     # based upon the BOM bytes, and then decodes the contents so that
@@ -2477,7 +2653,7 @@ class File(Base):
         """
         if not self.rexists():
             return SCons.Util.MD5signature('')
-        fname = self.rfile().abspath
+        fname = self.rfile().get_abspath()
         try:
             cs = SCons.Util.MD5filesignature(fname,
                 chunksize=SCons.Node.FS.File.md5_chunksize*1024)
@@ -2487,9 +2663,7 @@ class File(Base):
             raise
         return cs
         
-
-    memoizer_counters.append(SCons.Memoize.CountValue('get_size'))
-
+    @SCons.Memoize.CountMethodCall
     def get_size(self):
         try:
             return self._memo['get_size']
@@ -2505,8 +2679,7 @@ class File(Base):
 
         return size
 
-    memoizer_counters.append(SCons.Memoize.CountValue('get_timestamp'))
-
+    @SCons.Memoize.CountMethodCall
     def get_timestamp(self):
         try:
             return self._memo['get_timestamp']
@@ -2522,14 +2695,6 @@ class File(Base):
 
         return timestamp
 
-    def store_info(self):
-        # Merge our build information into the already-stored entry.
-        # This accomodates "chained builds" where a file that's a target
-        # in one build (SConstruct file) is a source in a different build.
-        # See test/chained-build.py for the use case.
-        if do_store_info:
-            self.dir.sconsign().store_info(self.name, self)
-
     convert_copy_attrs = [
         'bsources',
         'bimplicit',
@@ -2642,8 +2807,7 @@ class File(Base):
             delattr(old_entry, attr)
         return new_entry
 
-    memoizer_counters.append(SCons.Memoize.CountValue('get_stored_info'))
-
+    @SCons.Memoize.CountMethodCall
     def get_stored_info(self):
         try:
             return self._memo['get_stored_info']
@@ -2683,8 +2847,7 @@ class File(Base):
     def _get_found_includes_key(self, env, scanner, path):
         return (id(env), id(scanner), path)
 
-    memoizer_counters.append(SCons.Memoize.CountDict('get_found_includes', _get_found_includes_key))
-
+    @SCons.Memoize.CountDictCall(_get_found_includes_key)
     def get_found_includes(self, env, scanner, path):
         """Return the included implicit dependencies in this file.
         Cache results so we only scan the file once per path
@@ -2768,9 +2931,9 @@ class File(Base):
             # any build information that's stored in the .sconsign file
             # into our binfo object so it doesn't get lost.
             old = self.get_stored_info()
-            self.get_binfo().__dict__.update(old.binfo.__dict__)
+            self.get_binfo().merge(old.binfo)
 
-        self.store_info()
+        SCons.Node.store_info_map[self.store_info](self)
 
     def release_target_info(self):
         """Called just after this node has been marked
@@ -2870,7 +3033,7 @@ class File(Base):
 
     def _rmv_existing(self):
         self.clear_memoized_values()
-        if print_duplicate:
+        if SCons.Node.print_duplicate:
             print "dup: removing existing target %s"%self
         e = Unlink(self, [], None)
         if isinstance(e, SCons.Errors.BuildError):
@@ -2906,18 +3069,18 @@ class File(Base):
     def remove(self):
         """Remove this file."""
         if self.exists() or self.islink():
-            self.fs.unlink(self.path)
+            self.fs.unlink(self.get_internal_path())
             return 1
         return None
 
     def do_duplicate(self, src):
         self._createDir()
-        if print_duplicate:
+        if SCons.Node.print_duplicate:
             print "dup: relinking variant '%s' from '%s'"%(self, src)
         Unlink(self, None, None)
         e = Link(self, src, None)
         if isinstance(e, SCons.Errors.BuildError):
-            desc = "Cannot duplicate `%s' in `%s': %s." % (src.path, self.dir.path, e.errstr)
+            desc = "Cannot duplicate `%s' in `%s': %s." % (src.get_internal_path(), self.dir.path, e.errstr)
             raise SCons.Errors.StopError(desc)
         self.linked = 1
         # The Link() action may or may not have actually
@@ -2926,36 +3089,14 @@ class File(Base):
         # _rexists attributes so they can be reevaluated.
         self.clear()
 
-    memoizer_counters.append(SCons.Memoize.CountValue('exists'))
-
+    @SCons.Memoize.CountMethodCall
     def exists(self):
         try:
             return self._memo['exists']
         except KeyError:
             pass
-        # Duplicate from source path if we are set up to do this.
-        if self.duplicate and not self.is_derived() and not self.linked:
-            src = self.srcnode()
-            if src is not self:
-                # At this point, src is meant to be copied in a variant directory.
-                src = src.rfile()
-                if src.abspath != self.abspath:
-                    if src.exists():
-                        self.do_duplicate(src)
-                        # Can't return 1 here because the duplication might
-                        # not actually occur if the -n option is being used.
-                    else:
-                        # The source file does not exist.  Make sure no old
-                        # copy remains in the variant directory.
-                        if print_duplicate:
-                            print "dup: no src for %s, unlinking old variant copy"%self
-                        if Base.exists(self) or self.islink():
-                            self.fs.unlink(self.path)
-                        # Return None explicitly because the Base.exists() call
-                        # above will have cached its value if the file existed.
-                        self._memo['exists'] = None
-                        return None
-        result = Base.exists(self)
+        
+        result = SCons.Node._exists_map[self._func_exists](self)
         self._memo['exists'] = result
         return result
 
@@ -3032,7 +3173,7 @@ class File(Base):
 
     def builder_set(self, builder):
         SCons.Node.Node.builder_set(self, builder)
-        self.changed_since_last_build = self.decide_target
+        self.changed_since_last_build = 5
 
     def built(self):
         """Called just after this File node is successfully built.
@@ -3049,7 +3190,7 @@ class File(Base):
         if (not SCons.Node.interactive and 
             not hasattr(self.attributes, 'keep_targetinfo')):
             # Ensure that the build infos get computed and cached...        
-            self.store_info()
+            SCons.Node.store_info_map[self.store_info](self)
             # ... then release some more variables.
             self._specific_sources = False
             self.labspath = None
@@ -3111,16 +3252,6 @@ class File(Base):
         except AttributeError:
             return 1
 
-    def decide_source(self, target, prev_ni):
-        return target.get_build_env().decide_source(self, target, prev_ni)
-
-    def decide_target(self, target, prev_ni):
-        return target.get_build_env().decide_target(self, target, prev_ni)
-
-    # Initialize this Node's decider function to decide_source() because
-    # every file is a source file until it has a Builder attached...
-    changed_since_last_build = decide_source
-
     def is_up_to_date(self):
         T = 0
         if T: Trace('is_up_to_date(%s):' % self)
@@ -3138,7 +3269,7 @@ class File(Base):
                         e = LocalCopy(self, r, None)
                         if isinstance(e, SCons.Errors.BuildError):
                             raise 
-                        self.store_info()
+                        SCons.Node.store_info_map[self.store_info](self)
                     if T: Trace(' 1\n')
                     return 1
             self.changed()
@@ -3149,8 +3280,7 @@ class File(Base):
             if T: Trace(' self.exists():  %s\n' % r)
             return not r
 
-    memoizer_counters.append(SCons.Memoize.CountValue('rfile'))
-
+    @SCons.Memoize.CountMethodCall
     def rfile(self):
         try:
             return self._memo['rfile']
@@ -3252,7 +3382,7 @@ class File(Base):
         # Append this node's signature...
         sigs.append(self.get_contents_sig())
         # ...and it's path
-        sigs.append(self.path)
+        sigs.append(self.get_internal_path())
         # Merge this all into a single signature
         result = self.cachesig = SCons.Util.MD5collect(sigs)
         return result
@@ -3268,10 +3398,6 @@ def get_default_fs():
 class FileFinder(object):
     """
     """
-    if SCons.Memoize.use_memoizer:
-        __metaclass__ = SCons.Memoize.Memoized_Metaclass
-
-    memoizer_counters = []
 
     def __init__(self):
         self._memo = {}
@@ -3314,8 +3440,7 @@ class FileFinder(object):
     def _find_file_key(self, filename, paths, verbose=None):
         return (filename, paths)
         
-    memoizer_counters.append(SCons.Memoize.CountDict('find_file', _find_file_key))
-
+    @SCons.Memoize.CountDictCall(_find_file_key)
     def find_file(self, filename, paths, verbose=None):
         """
         find_file(str, [Dir()]) -> [nodes]
diff --git a/src/engine/SCons/Node/FSTests.py b/src/engine/SCons/Node/FSTests.py
index 0326717..0c1e71f 100644
--- a/src/engine/SCons/Node/FSTests.py
+++ b/src/engine/SCons/Node/FSTests.py
@@ -130,34 +130,34 @@ class VariantDirTestCase(unittest.TestCase):
         fs.VariantDir('build', 'src')
         f2 = fs.File('build/test2')
         d1 = fs.Dir('build')
-        assert f1.srcnode().path == os.path.normpath('src/test1'), f1.srcnode().path
-        assert f2.srcnode().path == os.path.normpath('src/test2'), f2.srcnode().path
-        assert d1.srcnode().path == 'src', d1.srcnode().path
+        assert f1.srcnode().get_internal_path() == os.path.normpath('src/test1'), f1.srcnode().get_internal_path()
+        assert f2.srcnode().get_internal_path() == os.path.normpath('src/test2'), f2.srcnode().get_internal_path()
+        assert d1.srcnode().get_internal_path() == 'src', d1.srcnode().get_internal_path()
 
         fs = SCons.Node.FS.FS()
         f1 = fs.File('build/test1')
         fs.VariantDir('build', '.')
         f2 = fs.File('build/test2')
         d1 = fs.Dir('build')
-        assert f1.srcnode().path == 'test1', f1.srcnode().path
-        assert f2.srcnode().path == 'test2', f2.srcnode().path
-        assert d1.srcnode().path == '.', d1.srcnode().path
+        assert f1.srcnode().get_internal_path() == 'test1', f1.srcnode().get_internal_path()
+        assert f2.srcnode().get_internal_path() == 'test2', f2.srcnode().get_internal_path()
+        assert d1.srcnode().get_internal_path() == '.', d1.srcnode().get_internal_path()
 
         fs = SCons.Node.FS.FS()
         fs.VariantDir('build/var1', 'src')
         fs.VariantDir('build/var2', 'src')
         f1 = fs.File('build/var1/test1')
         f2 = fs.File('build/var2/test1')
-        assert f1.srcnode().path == os.path.normpath('src/test1'), f1.srcnode().path
-        assert f2.srcnode().path == os.path.normpath('src/test1'), f2.srcnode().path
+        assert f1.srcnode().get_internal_path() == os.path.normpath('src/test1'), f1.srcnode().get_internal_path()
+        assert f2.srcnode().get_internal_path() == os.path.normpath('src/test1'), f2.srcnode().get_internal_path()
 
         fs = SCons.Node.FS.FS()
         fs.VariantDir('../var1', 'src')
         fs.VariantDir('../var2', 'src')
         f1 = fs.File('../var1/test1')
         f2 = fs.File('../var2/test1')
-        assert f1.srcnode().path == os.path.normpath('src/test1'), f1.srcnode().path
-        assert f2.srcnode().path == os.path.normpath('src/test1'), f2.srcnode().path
+        assert f1.srcnode().get_internal_path() == os.path.normpath('src/test1'), f1.srcnode().get_internal_path()
+        assert f2.srcnode().get_internal_path() == os.path.normpath('src/test1'), f2.srcnode().get_internal_path()
 
         # Set up some files
         test.subdir('work', ['work', 'src'])
@@ -210,8 +210,8 @@ class VariantDirTestCase(unittest.TestCase):
         f2out_2.builder = 1
         fs.Repository(test.workpath('rep1'))
 
-        assert f1.srcnode().path == os.path.normpath('src/test.in'),\
-               f1.srcnode().path
+        assert f1.srcnode().get_internal_path() == os.path.normpath('src/test.in'),\
+               f1.srcnode().get_internal_path()
         # str(node) returns source path for duplicate = 0
         assert str(f1) == os.path.normpath('src/test.in'), str(f1)
         # Build path does not exist
@@ -221,11 +221,11 @@ class VariantDirTestCase(unittest.TestCase):
         # And duplicate=0 should also work just like a Repository
         assert f1.rexists()
         # rfile() should point to the source path
-        assert f1.rfile().path == os.path.normpath('src/test.in'),\
-               f1.rfile().path
+        assert f1.rfile().get_internal_path() == os.path.normpath('src/test.in'),\
+               f1.rfile().get_internal_path()
 
-        assert f2.srcnode().path == os.path.normpath('src/test.in'),\
-               f2.srcnode().path
+        assert f2.srcnode().get_internal_path() == os.path.normpath('src/test.in'),\
+               f2.srcnode().get_internal_path()
         # str(node) returns build path for duplicate = 1
         assert str(f2) == os.path.normpath('build/var2/test.in'), str(f2)
         # Build path exists
@@ -239,8 +239,8 @@ class VariantDirTestCase(unittest.TestCase):
         f3 = fs.File('build/var1/test2.in')
         f4 = fs.File('build/var2/test2.in')
 
-        assert f3.srcnode().path == os.path.normpath('src/test2.in'),\
-               f3.srcnode().path
+        assert f3.srcnode().get_internal_path() == os.path.normpath('src/test2.in'),\
+               f3.srcnode().get_internal_path()
         # str(node) returns source path for duplicate = 0
         assert str(f3) == os.path.normpath('src/test2.in'), str(f3)
         # Build path does not exist
@@ -250,11 +250,11 @@ class VariantDirTestCase(unittest.TestCase):
         # But we do have a file in the Repository
         assert f3.rexists()
         # rfile() should point to the source path
-        assert f3.rfile().path == os.path.normpath(test.workpath('rep1/src/test2.in')),\
-               f3.rfile().path
+        assert f3.rfile().get_internal_path() == os.path.normpath(test.workpath('rep1/src/test2.in')),\
+               f3.rfile().get_internal_path()
 
-        assert f4.srcnode().path == os.path.normpath('src/test2.in'),\
-               f4.srcnode().path
+        assert f4.srcnode().get_internal_path() == os.path.normpath('src/test2.in'),\
+               f4.srcnode().get_internal_path()
         # str(node) returns build path for duplicate = 1
         assert str(f4) == os.path.normpath('build/var2/test2.in'), str(f4)
         # Build path should exist
@@ -264,8 +264,8 @@ class VariantDirTestCase(unittest.TestCase):
         # should exist in repository, since exists() is true
         assert f4.rexists()
         # rfile() should point to ourselves
-        assert f4.rfile().path == os.path.normpath('build/var2/test2.in'),\
-               f4.rfile().path
+        assert f4.rfile().get_internal_path() == os.path.normpath('build/var2/test2.in'),\
+               f4.rfile().get_internal_path()
 
         f5 = fs.File('build/var1/test.out')
         f6 = fs.File('build/var2/test.out')
@@ -285,14 +285,14 @@ class VariantDirTestCase(unittest.TestCase):
 
         assert not f7.exists()
         assert f7.rexists()
-        r = f7.rfile().path
+        r = f7.rfile().get_internal_path()
         expect = os.path.normpath(test.workpath('rep1/build/var1/test2.out'))
         assert r == expect, (repr(r), repr(expect))
 
         assert not f8.exists()
         assert f8.rexists()
-        assert f8.rfile().path == os.path.normpath(test.workpath('rep1/build/var2/test2.out')),\
-               f8.rfile().path
+        assert f8.rfile().get_internal_path() == os.path.normpath(test.workpath('rep1/build/var2/test2.out')),\
+               f8.rfile().get_internal_path()
 
         # Verify the Mkdir and Link actions are called
         d9 = fs.Dir('build/var2/new_dir')
@@ -319,9 +319,9 @@ class VariantDirTestCase(unittest.TestCase):
             d9.reset_executor()
             f9.exists()
             expect = os.path.join('build', 'var2', 'new_dir')
-            assert dir_made[0].path == expect, dir_made[0].path
+            assert dir_made[0].get_internal_path() == expect, dir_made[0].get_internal_path()
             expect = os.path.join('build', 'var2', 'new_dir', 'test9.out')
-            assert link_made[0].path == expect, link_made[0].path
+            assert link_made[0].get_internal_path() == expect, link_made[0].get_internal_path()
             assert f9.linked
         finally:
             SCons.Node.FS.Link = save_Link
@@ -338,7 +338,7 @@ class VariantDirTestCase(unittest.TestCase):
 
         f11 = fs.File('src/file11')
         t, m = f11.alter_targets()
-        bdt = [n.path for n in t]
+        bdt = [n.get_internal_path() for n in t]
         var1_file11 = os.path.normpath('build/var1/file11')
         var2_file11 = os.path.normpath('build/var2/file11')
         assert bdt == [var1_file11, var2_file11], bdt
@@ -346,11 +346,11 @@ class VariantDirTestCase(unittest.TestCase):
         f12 = fs.File('src/file12')
         f12.builder = 1
         bdt, m = f12.alter_targets()
-        assert bdt == [], [n.path for n in bdt]
+        assert bdt == [], [n.get_internal_path() for n in bdt]
 
         d13 = fs.Dir('src/new_dir')
         t, m = d13.alter_targets()
-        bdt = [n.path for n in t]
+        bdt = [n.get_internal_path() for n in t]
         var1_new_dir = os.path.normpath('build/var1/new_dir')
         var2_new_dir = os.path.normpath('build/var2/new_dir')
         assert bdt == [var1_new_dir, var2_new_dir], bdt
@@ -566,13 +566,13 @@ class VariantDirTestCase(unittest.TestCase):
             f = dir + '/f'
             fnode = fs.File(dir + '/f')
 
-            dp = dnode.srcnode().path
+            dp = dnode.srcnode().get_internal_path()
             expect = os.path.normpath(srcnode_map.get(dir, dir))
             if dp != expect:
                 print "Dir `%s' srcnode() `%s' != expected `%s'" % (dir, dp, expect)
                 errors = errors + 1
 
-            fp = fnode.srcnode().path
+            fp = fnode.srcnode().get_internal_path()
             expect = os.path.normpath(srcnode_map.get(f, f))
             if fp != expect:
                 print "File `%s' srcnode() `%s' != expected `%s'" % (f, fp, expect)
@@ -584,14 +584,14 @@ class VariantDirTestCase(unittest.TestCase):
             fnode = fs.File(dir + '/f')
 
             t, m = dnode.alter_targets()
-            tp = t[0].path
+            tp = t[0].get_internal_path()
             expect = os.path.normpath(alter_map.get(dir, dir))
             if tp != expect:
                 print "Dir `%s' alter_targets() `%s' != expected `%s'" % (dir, tp, expect)
                 errors = errors + 1
 
             t, m = fnode.alter_targets()
-            tp = t[0].path
+            tp = t[0].get_internal_path()
             expect = os.path.normpath(alter_map.get(f, f))
             if tp != expect:
                 print "File `%s' alter_targets() `%s' != expected `%s'" % (f, tp, expect)
@@ -698,19 +698,19 @@ class DirNodeInfoTestCase(_tempdirTestCase):
     def test___init__(self):
         """Test DirNodeInfo initialization"""
         ddd = self.fs.Dir('ddd')
-        ni = SCons.Node.FS.DirNodeInfo(ddd)
+        ni = SCons.Node.FS.DirNodeInfo()
 
 class DirBuildInfoTestCase(_tempdirTestCase):
     def test___init__(self):
         """Test DirBuildInfo initialization"""
         ddd = self.fs.Dir('ddd')
-        bi = SCons.Node.FS.DirBuildInfo(ddd)
+        bi = SCons.Node.FS.DirBuildInfo()
 
 class FileNodeInfoTestCase(_tempdirTestCase):
     def test___init__(self):
         """Test FileNodeInfo initialization"""
         fff = self.fs.File('fff')
-        ni = SCons.Node.FS.FileNodeInfo(fff)
+        ni = SCons.Node.FS.FileNodeInfo()
         assert isinstance(ni, SCons.Node.FS.FileNodeInfo)
 
     def test_update(self):
@@ -718,7 +718,7 @@ class FileNodeInfoTestCase(_tempdirTestCase):
         test = self.test
         fff = self.fs.File('fff')
 
-        ni = SCons.Node.FS.FileNodeInfo(fff)
+        ni = SCons.Node.FS.FileNodeInfo()
 
         test.write('fff', "fff\n")
 
@@ -765,37 +765,41 @@ class FileBuildInfoTestCase(_tempdirTestCase):
     def test___init__(self):
         """Test File.BuildInfo initialization"""
         fff = self.fs.File('fff')
-        bi = SCons.Node.FS.FileBuildInfo(fff)
+        bi = SCons.Node.FS.FileBuildInfo()
         assert bi, bi
 
     def test_convert_to_sconsign(self):
         """Test converting to .sconsign file format"""
         fff = self.fs.File('fff')
-        bi = SCons.Node.FS.FileBuildInfo(fff)
+        bi = SCons.Node.FS.FileBuildInfo()
         assert hasattr(bi, 'convert_to_sconsign')
 
     def test_convert_from_sconsign(self):
         """Test converting from .sconsign file format"""
         fff = self.fs.File('fff')
-        bi = SCons.Node.FS.FileBuildInfo(fff)
+        bi = SCons.Node.FS.FileBuildInfo()
         assert hasattr(bi, 'convert_from_sconsign')
 
     def test_prepare_dependencies(self):
         """Test that we have a prepare_dependencies() method"""
         fff = self.fs.File('fff')
-        bi = SCons.Node.FS.FileBuildInfo(fff)
+        bi = SCons.Node.FS.FileBuildInfo()
         bi.prepare_dependencies()
 
     def test_format(self):
         """Test the format() method"""
         f1 = self.fs.File('f1')
-        bi1 = SCons.Node.FS.FileBuildInfo(f1)
+        bi1 = SCons.Node.FS.FileBuildInfo()
 
-        s1sig = SCons.Node.FS.FileNodeInfo(self.fs.File('n1'))
+        self.fs.File('n1')
+        self.fs.File('n2')
+        self.fs.File('n3')
+
+        s1sig = SCons.Node.FS.FileNodeInfo()
         s1sig.csig = 1
-        d1sig = SCons.Node.FS.FileNodeInfo(self.fs.File('n2'))
+        d1sig = SCons.Node.FS.FileNodeInfo()
         d1sig.timestamp = 2
-        i1sig = SCons.Node.FS.FileNodeInfo(self.fs.File('n3'))
+        i1sig = SCons.Node.FS.FileNodeInfo()
         i1sig.size = 3
 
         bi1.bsources = [self.fs.File('s1')]
@@ -953,7 +957,7 @@ class FSTestCase(_tempdirTestCase):
         assert isinstance(f1, SCons.Node.FS.File)
 
         d1_f1 = os.path.join('d1', 'f1')
-        assert f1.path == d1_f1, "f1.path %s != %s" % (f1.path, d1_f1)
+        assert f1.get_internal_path() == d1_f1, "f1.path %s != %s" % (f1.get_internal_path(), d1_f1)
         assert str(f1) == d1_f1, "str(f1) %s != %s" % (str(f1), d1_f1)
 
         x1 = d1.File('x1')
@@ -1045,16 +1049,16 @@ class FSTestCase(_tempdirTestCase):
                     name = os.sep
 
             if dir.up() is None:
-                dir_up_path =  dir.path
+                dir_up_path =  dir.get_internal_path()
             else:
-                dir_up_path =  dir.up().path
+                dir_up_path =  dir.up().get_internal_path()
 
             assert dir.name == name, \
                    "dir.name %s != expected name %s" % \
                    (dir.name, name)
-            assert dir.path == path, \
+            assert dir.get_internal_path() == path, \
                    "dir.path %s != expected path %s" % \
-                   (dir.path, path)
+                   (dir.get_internal_path(), path)
             assert str(dir) == path, \
                    "str(dir) %s != expected path %s" % \
                    (str(dir), path)
@@ -1136,9 +1140,9 @@ class FSTestCase(_tempdirTestCase):
         # Test for a bug in 0.04 that did not like looking up
         # dirs with a trailing slash on Windows.
         d=fs.Dir('./')
-        assert d.path == '.', d.abspath
+        assert d.get_internal_path() == '.', d.get_abspath()
         d=fs.Dir('foo/')
-        assert d.path == 'foo', d.abspath
+        assert d.get_internal_path() == 'foo', d.get_abspath()
 
         # Test for sub-classing of node building.
         global built_it
@@ -1167,50 +1171,50 @@ class FSTestCase(_tempdirTestCase):
 
         e1 = fs.Entry("d1")
         assert e1.__class__.__name__ == 'Dir'
-        match(e1.path, "d1")
-        match(e1.dir.path, ".")
+        match(e1.get_internal_path(), "d1")
+        match(e1.dir.get_internal_path(), ".")
 
         e2 = fs.Entry("d1/f1")
         assert e2.__class__.__name__ == 'File'
-        match(e2.path, "d1/f1")
-        match(e2.dir.path, "d1")
+        match(e2.get_internal_path(), "d1/f1")
+        match(e2.dir.get_internal_path(), "d1")
 
         e3 = fs.Entry("e3")
         assert e3.__class__.__name__ == 'Entry'
-        match(e3.path, "e3")
-        match(e3.dir.path, ".")
+        match(e3.get_internal_path(), "e3")
+        match(e3.dir.get_internal_path(), ".")
 
         e4 = fs.Entry("d1/e4")
         assert e4.__class__.__name__ == 'Entry'
-        match(e4.path, "d1/e4")
-        match(e4.dir.path, "d1")
+        match(e4.get_internal_path(), "d1/e4")
+        match(e4.dir.get_internal_path(), "d1")
 
         e5 = fs.Entry("e3/e5")
         assert e3.__class__.__name__ == 'Dir'
-        match(e3.path, "e3")
-        match(e3.dir.path, ".")
+        match(e3.get_internal_path(), "e3")
+        match(e3.dir.get_internal_path(), ".")
         assert e5.__class__.__name__ == 'Entry'
-        match(e5.path, "e3/e5")
-        match(e5.dir.path, "e3")
+        match(e5.get_internal_path(), "e3/e5")
+        match(e5.dir.get_internal_path(), "e3")
 
         e6 = fs.Dir("d1/e4")
         assert e6 is e4
         assert e4.__class__.__name__ == 'Dir'
-        match(e4.path, "d1/e4")
-        match(e4.dir.path, "d1")
+        match(e4.get_internal_path(), "d1/e4")
+        match(e4.dir.get_internal_path(), "d1")
 
         e7 = fs.File("e3/e5")
         assert e7 is e5
         assert e5.__class__.__name__ == 'File'
-        match(e5.path, "e3/e5")
-        match(e5.dir.path, "e3")
+        match(e5.get_internal_path(), "e3/e5")
+        match(e5.dir.get_internal_path(), "e3")
 
         fs.chdir(fs.Dir('subdir'))
         f11 = fs.File("f11")
-        match(f11.path, "subdir/f11")
+        match(f11.get_internal_path(), "subdir/f11")
         d12 = fs.Dir("d12")
         e13 = fs.Entry("subdir/e13")
-        match(e13.path, "subdir/subdir/e13")
+        match(e13.get_internal_path(), "subdir/subdir/e13")
         fs.chdir(fs.Dir('..'))
 
         # Test scanning
@@ -1220,13 +1224,13 @@ class FSTestCase(_tempdirTestCase):
         f1.builder.target_scanner = Scanner(xyz)
 
         f1.scan()
-        assert f1.implicit[0].path == "xyz"
+        assert f1.implicit[0].get_internal_path() == "xyz"
         f1.implicit = []
         f1.scan()
         assert f1.implicit == []
         f1.implicit = None
         f1.scan()
-        assert f1.implicit[0].path == "xyz"
+        assert f1.implicit[0].get_internal_path() == "xyz"
 
         # Test underlying scanning functionality in get_found_includes()
         env = Environment()
@@ -1284,9 +1288,9 @@ class FSTestCase(_tempdirTestCase):
         fs.chdir(fs.Dir('subdir'))
         # The cwd's path is always "."
         assert str(fs.getcwd()) == ".", str(fs.getcwd())
-        assert fs.getcwd().path == 'subdir', fs.getcwd().path
+        assert fs.getcwd().get_internal_path() == 'subdir', fs.getcwd().get_internal_path()
         fs.chdir(fs.Dir('../..'))
-        assert fs.getcwd().path == test.workdir, fs.getcwd().path
+        assert fs.getcwd().get_internal_path() == test.workdir, fs.getcwd().get_internal_path()
 
         f1 = fs.File(test.workpath("do_i_exist"))
         assert not f1.exists()
@@ -1589,15 +1593,15 @@ class FSTestCase(_tempdirTestCase):
             assert dir.name == name, \
                    "dir.name %s != expected name %s" % \
                    (dir.name, name)
-            assert dir.path == path, \
+            assert dir.get_internal_path() == path, \
                    "dir.path %s != expected path %s" % \
-                   (dir.path, path)
+                   (dir.get_internal_path(), path)
             assert str(dir) == path, \
                    "str(dir) %s != expected path %s" % \
                    (str(dir), path)
-            assert dir.up().path == up_path, \
+            assert dir.up().get_internal_path() == up_path, \
                    "dir.up().path %s != expected parent path %s" % \
-                   (dir.up().path, up_path)
+                   (dir.up().get_internal_path(), up_path)
 
         save_os_path = os.path
         save_os_sep = os.sep
@@ -1691,22 +1695,22 @@ class FSTestCase(_tempdirTestCase):
                 name = path.split(os.sep)[-1]
 
             if dir.up() is None:
-                dir_up_path =  dir.path
+                dir_up_path =  dir.get_internal_path()
             else:
-                dir_up_path =  dir.up().path
+                dir_up_path =  dir.up().get_internal_path()
 
             assert dir.name == name, \
                    "dir.name %s != expected name %s" % \
                    (dir.name, name)
-            assert dir.path == path, \
+            assert dir.get_internal_path() == path, \
                    "dir.path %s != expected path %s" % \
-                   (dir.path, path)
+                   (dir.get_internal_path(), path)
             assert str(dir) == path, \
                    "str(dir) %s != expected path %s" % \
                    (str(dir), path)
             assert dir_up_path == up_path, \
                    "dir.up().path %s != expected parent path %s" % \
-                   (dir.up().path, up_path)
+                   (dir.up().get_internal_path(), up_path)
 
         save_os_path = os.path
         save_os_sep = os.sep
@@ -1792,7 +1796,7 @@ class FSTestCase(_tempdirTestCase):
 
         d1 = fs.Dir('d1')
         d2 = d1.Dir('d2')
-        dirs = os.path.normpath(d2.abspath).split(os.sep)
+        dirs = os.path.normpath(d2.get_abspath()).split(os.sep)
         above_path = os.path.join(*['..']*len(dirs) + ['above'])
         above = d2.Dir(above_path)
 
@@ -1831,9 +1835,9 @@ class FSTestCase(_tempdirTestCase):
         fs = self.fs
         if sys.platform not in ('win32',):
             return
-        p = fs.Dir(r"\\computername\sharename").abspath
+        p = fs.Dir(r"\\computername\sharename").get_abspath()
         assert p == r"\\computername\sharename", p
-        p = fs.Dir(r"\\\computername\sharename").abspath
+        p = fs.Dir(r"\\\computername\sharename").get_abspath()
         assert p == r"\\computername\sharename", p
 
     def test_rel_path(self):
@@ -1980,7 +1984,7 @@ class DirTestCase(_tempdirTestCase):
         fs.Dir(os.path.join('ddd', 'd1', 'f4'))
         fs.Dir(os.path.join('ddd', 'd1', 'f5'))
         dir.scan()
-        kids = sorted([x.path for x in dir.children(None)])
+        kids = sorted([x.get_internal_path() for x in dir.children(None)])
         assert kids == [os.path.join('ddd', 'd1'),
                         os.path.join('ddd', 'f1'),
                         os.path.join('ddd', 'f2'),
@@ -2024,12 +2028,12 @@ class DirTestCase(_tempdirTestCase):
 
         fs.File(os.path.join('ddd', 'f1'))
         dir.scan()
-        kids = sorted([x.path for x in dir.children()])
+        kids = sorted([x.get_internal_path() for x in dir.children()])
         assert kids == [os.path.join('ddd', 'f1')], kids
 
         fs.File(os.path.join('ddd', 'f2'))
         dir.scan()
-        kids = sorted([x.path for x in dir.children()])
+        kids = sorted([x.get_internal_path() for x in dir.children()])
         assert kids == [os.path.join('ddd', 'f1'),
                         os.path.join('ddd', 'f2')], kids
 
@@ -2171,8 +2175,12 @@ class DirTestCase(_tempdirTestCase):
         """
         test = self.test
 
-        return_true = lambda: 1
+        def return_true(node):
+            return 1
 
+        SCons.Node._is_derived_map[2] = return_true
+        SCons.Node._exists_map[5] = return_true
+        
         test.subdir('src0')
         test.write(['src0', 'on-disk-f1'], "src0/on-disk-f1\n")
         test.write(['src0', 'on-disk-f2'], "src0/on-disk-f2\n")
@@ -2184,14 +2192,14 @@ class DirTestCase(_tempdirTestCase):
         self.fs.VariantDir(bld0, src0, duplicate=0)
 
         derived_f = src0.File('derived-f')
-        derived_f.is_derived = return_true
+        derived_f._func_is_derived = 2
         exists_f = src0.File('exists-f')
-        exists_f.exists = return_true
+        exists_f._func_exists = 5
 
         derived_e = src0.Entry('derived-e')
-        derived_e.is_derived = return_true
+        derived_e._func_is_derived = 2
         exists_e = src0.Entry('exists-e')
-        exists_e.exists = return_true
+        exists_e._func_exists = 5
 
         def check(result, expect):
             result = list(map(str, result))
@@ -2245,14 +2253,14 @@ class DirTestCase(_tempdirTestCase):
         self.fs.VariantDir(bld1, src1, duplicate=1)
 
         derived_f = src1.File('derived-f')
-        derived_f.is_derived = return_true
+        derived_f._func_is_derived = 2
         exists_f = src1.File('exists-f')
-        exists_f.exists = return_true
+        exists_f._func_exists = 5
 
         derived_e = src1.Entry('derived-e')
-        derived_e.is_derived = return_true
+        derived_e._func_is_derived = 2
         exists_e = src1.Entry('exists-e')
-        exists_e.exists = return_true
+        exists_e._func_exists = 5
 
         # First check from the source directory.
         n = src1.srcdir_find_file('does_not_exist')
@@ -2432,7 +2440,7 @@ class FileTestCase(_tempdirTestCase):
         build_f1 = fs.File('build/f1')
 
         assert build_f1.exists(), "%s did not realize that %s exists" % (build_f1, src_f1)
-        assert os.path.exists(build_f1.abspath), "%s did not get duplicated on disk" % build_f1.abspath
+        assert os.path.exists(build_f1.get_abspath()), "%s did not get duplicated on disk" % build_f1.get_abspath()
 
         test.unlink(['src', 'f1'])
         src_f1.clear()  # so the next exists() call will look on disk again
@@ -2441,7 +2449,7 @@ class FileTestCase(_tempdirTestCase):
         build_f1.clear()
         build_f1.linked = None
         assert not build_f1.exists(), "%s did not realize that %s disappeared" % (build_f1, src_f1)
-        assert not os.path.exists(build_f1.abspath), "%s did not get removed after %s was removed" % (build_f1, src_f1)
+        assert not os.path.exists(build_f1.get_abspath()), "%s did not get removed after %s was removed" % (build_f1, src_f1)
 
 
 
@@ -2535,7 +2543,7 @@ class GlobTestCase(_tempdirTestCase):
         for input, string_expect, node_expect in cases:
             r = self.fs.Glob(input, **kwargs)
             if node_expect:
-                r = sorted(r, key=lambda a: a.path)
+                r = sorted(r, key=lambda a: a.get_internal_path())
                 result = []
                 for n in node_expect:
                     if isinstance(n, str):
@@ -2906,8 +2914,14 @@ class RepositoryTestCase(_tempdirTestCase):
 
     def test_rdir(self):
         """Test the Dir.rdir() method"""
-        return_true = lambda: 1
-        return_false = lambda: 0
+        def return_true(obj):
+            return 1
+        def return_false(obj):
+            return 0
+        SCons.Node._exists_map[5] = return_true
+        SCons.Node._exists_map[6] = return_false
+        SCons.Node._is_derived_map[2] = return_true
+        SCons.Node._is_derived_map[3] = return_false
 
         d1 = self.fs.Dir('d1')
         d2 = self.fs.Dir('d2')
@@ -2931,19 +2945,19 @@ class RepositoryTestCase(_tempdirTestCase):
         assert r == os.path.join(self.rep3, 'd3'), r
 
         e1 = self.fs.Dir('e1')
-        e1.exists = return_false
+        e1._func_exists = 6
         e2 = self.fs.Dir('e2')
-        e2.exists = return_false
+        e2._func_exists = 6
 
         # Make sure we match entries in repositories,
         # regardless of whether they're derived or not.
 
         re1 = self.fs.Entry(os.path.join(self.rep1, 'e1'))
-        re1.exists = return_true
-        re1.is_derived = return_true
+        re1._func_exists = 5
+        re1._func_is_derived = 2
         re2 = self.fs.Entry(os.path.join(self.rep2, 'e2'))
-        re2.exists = return_true
-        re2.is_derived = return_false
+        re2._func_exists = 5
+        re2._func_is_derived = 3
 
         r = e1.rdir()
         assert r is re1, r
@@ -2953,8 +2967,14 @@ class RepositoryTestCase(_tempdirTestCase):
 
     def test_rfile(self):
         """Test the File.rfile() method"""
-        return_true = lambda: 1
-        return_false = lambda: 0
+        def return_true(obj):
+            return 1
+        def return_false(obj):
+            return 0
+        SCons.Node._exists_map[5] = return_true
+        SCons.Node._exists_map[6] = return_false
+        SCons.Node._is_derived_map[2] = return_true
+        SCons.Node._is_derived_map[3] = return_false
 
         f1 = self.fs.File('f1')
         f2 = self.fs.File('f2')
@@ -2978,19 +2998,19 @@ class RepositoryTestCase(_tempdirTestCase):
         assert r == os.path.join(self.rep3, 'f3'), r
 
         e1 = self.fs.File('e1')
-        e1.exists = return_false
+        e1._func_exists = 6
         e2 = self.fs.File('e2')
-        e2.exists = return_false
+        e2._func_exists = 6
 
         # Make sure we match entries in repositories,
         # regardless of whether they're derived or not.
 
         re1 = self.fs.Entry(os.path.join(self.rep1, 'e1'))
-        re1.exists = return_true
-        re1.is_derived = return_true
+        re1._func_exists = 5
+        re1._func_is_derived = 2
         re2 = self.fs.Entry(os.path.join(self.rep2, 'e2'))
-        re2.exists = return_true
-        re2.is_derived = return_false
+        re2._func_exists = 5
+        re2._func_is_derived = 3
 
         r = e1.rfile()
         assert r is re1, r
@@ -3244,9 +3264,13 @@ class stored_infoTestCase(unittest.TestCase):
                     self.xyzzy = 7
             def get_entry(self, name):
                 return self.Null()
+            
+        def test_sconsign(node):
+            return MySConsign()
 
         f = fs.File('file2', d)
-        f.dir.sconsign = MySConsign
+        SCons.Node.FS._sconsign_map[2] = test_sconsign
+        f.dir._func_sconsign = 2
         bi = f.get_stored_info()
         assert bi.xyzzy == 7, bi
 
@@ -3360,7 +3384,7 @@ class prepareTestCase(unittest.TestCase):
 
         xyz.set_state(0)
         xyz.prepare()
-        assert dir_made[0].path == "new_dir", dir_made[0]
+        assert dir_made[0].get_internal_path() == "new_dir", dir_made[0]
 
         dir = fs.Dir("dir")
         dir.prepare()
@@ -3373,7 +3397,7 @@ class SConstruct_dirTestCase(unittest.TestCase):
 
         fs = SCons.Node.FS.FS()
         fs.set_SConstruct_dir(fs.Dir('xxx'))
-        assert fs.SConstruct_dir.path == 'xxx'
+        assert fs.SConstruct_dir.get_internal_path() == 'xxx'
 
 
 
@@ -3552,7 +3576,7 @@ class SpecialAttrTestCase(unittest.TestCase):
         for_sig = f.suffix.for_signature()
         assert for_sig == 'baz.blat_suffix', for_sig
 
-        s = str(f.abspath)
+        s = str(f.get_abspath())
         assert s == test.workpath('work', 'foo', 'bar', 'baz.blat'), s
         assert f.abspath.is_literal(), f.abspath
         for_sig = f.abspath.for_signature()
diff --git a/src/engine/SCons/Node/NodeTests.py b/src/engine/SCons/Node/NodeTests.py
index da502b0..a6471b4 100644
--- a/src/engine/SCons/Node/NodeTests.py
+++ b/src/engine/SCons/Node/NodeTests.py
@@ -184,7 +184,7 @@ class Scanner(object):
     called = None
     def __call__(self, node):
         self.called = 1
-        return node.found_includes
+        return node.GetTag('found_includes')
     def path(self, env, dir, target=None, source=None):
         return ()
     def select(self, node):
@@ -200,7 +200,7 @@ class MyNode(SCons.Node.Node):
     def __init__(self, name):
         SCons.Node.Node.__init__(self)
         self.name = name
-        self.found_includes = []
+        self.Tag('found_includes', [])
     def __str__(self):
         return self.name
     def get_found_includes(self, env, scanner, target):
@@ -224,11 +224,18 @@ class Calculator(object):
 
 
 class NodeInfoBaseTestCase(unittest.TestCase):
+    # The abstract class NodeInfoBase has not enough default slots to perform
+    # the merge and format test (arbitrary attributes do not work). Do it with a
+    # derived class that does provide the slots.
 
     def test_merge(self):
         """Test merging NodeInfoBase attributes"""
-        ni1 = SCons.Node.NodeInfoBase(SCons.Node.Node())
-        ni2 = SCons.Node.NodeInfoBase(SCons.Node.Node())
+
+        class TestNodeInfo(SCons.Node.NodeInfoBase):
+            __slots__ = ('a1', 'a2', 'a3')
+
+        ni1 = TestNodeInfo()
+        ni2 = TestNodeInfo()
 
         ni1.a1 = 1
         ni1.a2 = 2
@@ -237,27 +244,32 @@ class NodeInfoBaseTestCase(unittest.TestCase):
         ni2.a3 = 333
 
         ni1.merge(ni2)
-        expect = {'a1':1, 'a2':222, 'a3':333, '_version_id':1}
-        assert ni1.__dict__ == expect, ni1.__dict__
+        assert ni1.a1 == 1, ni1.a1
+        assert ni1.a2 == 222, ni1.a2
+        assert ni1.a3 == 333, ni1.a3
 
     def test_update(self):
         """Test the update() method"""
-        ni = SCons.Node.NodeInfoBase(SCons.Node.Node())
+        ni = SCons.Node.NodeInfoBase()
         ni.update(SCons.Node.Node())
 
     def test_format(self):
         """Test the NodeInfoBase.format() method"""
-        ni1 = SCons.Node.NodeInfoBase(SCons.Node.Node())
+
+        class TestNodeInfo(SCons.Node.NodeInfoBase):
+            __slots__ = ('xxx', 'yyy', 'zzz')
+
+        ni1 = TestNodeInfo()
         ni1.xxx = 'x'
         ni1.yyy = 'y'
         ni1.zzz = 'z'
 
         f = ni1.format()
-        assert f == ['1', 'x', 'y', 'z'], f
+        assert f == ['x', 'y', 'z'], f
+ 
+        field_list = ['xxx', 'zzz', 'aaa']
 
-        ni1.field_list = ['xxx', 'zzz', 'aaa']
-
-        f = ni1.format()
+        f = ni1.format(field_list)
         assert f == ['x', 'z', 'None'], f
 
 
@@ -267,26 +279,26 @@ class BuildInfoBaseTestCase(unittest.TestCase):
     def test___init__(self):
         """Test BuildInfoBase initialization"""
         n = SCons.Node.Node()
-        bi = SCons.Node.BuildInfoBase(n)
+        bi = SCons.Node.BuildInfoBase()
         assert bi
 
     def test_merge(self):
         """Test merging BuildInfoBase attributes"""
         n1 = SCons.Node.Node()
-        bi1 = SCons.Node.BuildInfoBase(n1)
+        bi1 = SCons.Node.BuildInfoBase()
         n2 = SCons.Node.Node()
-        bi2 = SCons.Node.BuildInfoBase(n2)
+        bi2 = SCons.Node.BuildInfoBase()
 
-        bi1.a1 = 1
-        bi1.a2 = 2
+        bi1.bsources = 1
+        bi1.bdepends = 2
 
-        bi2.a2 = 222
-        bi2.a3 = 333
+        bi2.bdepends = 222
+        bi2.bact = 333
 
         bi1.merge(bi2)
-        assert bi1.a1 == 1, bi1.a1
-        assert bi1.a2 == 222, bi1.a2
-        assert bi1.a3 == 333, bi1.a3
+        assert bi1.bsources == 1, bi1.bsources
+        assert bi1.bdepends == 222, bi1.bdepends
+        assert bi1.bact == 333, bi1.bact
 
 
 class NodeTestCase(unittest.TestCase):
@@ -427,6 +439,7 @@ class NodeTestCase(unittest.TestCase):
     def test_built(self):
         """Test the built() method"""
         class SubNodeInfo(SCons.Node.NodeInfoBase):
+            __slots__ = ('updated',)
             def update(self, node):
                 self.updated = 1
         class SubNode(SCons.Node.Node):
@@ -434,7 +447,7 @@ class NodeTestCase(unittest.TestCase):
                 self.cleared = 1
 
         n = SubNode()
-        n.ninfo = SubNodeInfo(n)
+        n.ninfo = SubNodeInfo()
         n.built()
         assert n.cleared, n.cleared
         assert n.ninfo.updated, n.ninfo.cleared
@@ -568,32 +581,56 @@ class NodeTestCase(unittest.TestCase):
     def test_get_csig(self):
         """Test generic content signature calculation
         """
-        node = SCons.Node.Node()
-        node.get_contents = lambda: 444
-        result = node.get_csig()
-        assert result == '550a141f12de6341fba65b0ad0433500', result
+        
+        class TestNodeInfo(SCons.Node.NodeInfoBase):
+            __slots__ = ('csig',)
+        try:
+            SCons.Node.Node.NodeInfo = TestNodeInfo
+            def my_contents(obj):
+                return 444
+            SCons.Node._get_contents_map[4] = my_contents
+            node = SCons.Node.Node()
+            node._func_get_contents = 4
+            result = node.get_csig()
+            assert result == '550a141f12de6341fba65b0ad0433500', result
+        finally:
+            SCons.Node.Node.NodeInfo = SCons.Node.NodeInfoBase
 
     def test_get_cachedir_csig(self):
         """Test content signature calculation for CacheDir
         """
-        node = SCons.Node.Node()
-        node.get_contents = lambda: 555
-        result = node.get_cachedir_csig()
-        assert result == '15de21c670ae7c3f6f3f1f37029303c9', result
+        class TestNodeInfo(SCons.Node.NodeInfoBase):
+            __slots__ = ('csig',)
+        try:
+            SCons.Node.Node.NodeInfo = TestNodeInfo
+            def my_contents(obj):
+                return 555
+            SCons.Node._get_contents_map[4] = my_contents
+            node = SCons.Node.Node()
+            node._func_get_contents = 4
+            result = node.get_cachedir_csig()
+            assert result == '15de21c670ae7c3f6f3f1f37029303c9', result
+        finally:
+            SCons.Node.Node.NodeInfo = SCons.Node.NodeInfoBase
 
     def test_get_binfo(self):
         """Test fetching/creating a build information structure
         """
+        class TestNodeInfo(SCons.Node.NodeInfoBase):
+            __slots__ = ('csig',)
+        SCons.Node.Node.NodeInfo = TestNodeInfo
         node = SCons.Node.Node()
-
+ 
         binfo = node.get_binfo()
         assert isinstance(binfo, SCons.Node.BuildInfoBase), binfo
 
         node = SCons.Node.Node()
         d = SCons.Node.Node()
-        d.get_ninfo().csig = 777
+        ninfo = d.get_ninfo()
+        assert isinstance(ninfo, SCons.Node.NodeInfoBase), ninfo
         i = SCons.Node.Node()
-        i.get_ninfo().csig = 888
+        ninfo = i.get_ninfo()
+        assert isinstance(ninfo, SCons.Node.NodeInfoBase), ninfo
         node.depends = [d]
         node.implicit = [i]
 
@@ -655,7 +692,7 @@ class NodeTestCase(unittest.TestCase):
         """Test calling the method to store build information
         """
         node = SCons.Node.Node()
-        node.store_info()
+        SCons.Node.store_info_map[node.store_info](node)
 
     def test_get_stored_info(self):
         """Test calling the method to fetch stored build information
@@ -888,7 +925,7 @@ class NodeTestCase(unittest.TestCase):
         s = Scanner()
         d1 = MyNode("d1")
         d2 = MyNode("d2")
-        node.found_includes = [d1, d2]
+        node.Tag('found_includes', [d1, d2])
 
         # Simple return of the found includes
         deps = node.get_implicit_deps(env, s, target)
@@ -898,14 +935,14 @@ class NodeTestCase(unittest.TestCase):
         e = MyNode("eee")
         f = MyNode("fff")
         g = MyNode("ggg")
-        d1.found_includes = [e, f]
-        d2.found_includes = [e, f]
-        f.found_includes = [g]
+        d1.Tag('found_includes', [e, f])
+        d2.Tag('found_includes', [e, f])
+        f.Tag('found_includes', [g])
         deps = node.get_implicit_deps(env, s, target)
         assert deps == [d1, d2, e, f, g], list(map(str, deps))
 
         # Recursive scanning eliminates duplicates
-        e.found_includes = [f]
+        e.Tag('found_includes', [f])
         deps = node.get_implicit_deps(env, s, target)
         assert deps == [d1, d2, e, f, g], list(map(str, deps))
 
@@ -994,7 +1031,7 @@ class NodeTestCase(unittest.TestCase):
 
         s = Scanner()
         d = MyNode("ddd")
-        node.found_includes = [d]
+        node.Tag('found_includes', [d])
 
         node.builder.target_scanner = s
         assert node.implicit is None
@@ -1207,7 +1244,7 @@ class NodeTestCase(unittest.TestCase):
     def test_Annotate(self):
         """Test using an interface-specific Annotate function."""
         def my_annotate(node, self=self):
-            node.annotation = self.node_string
+            node.Tag('annotation', self.node_string)
 
         save_Annotate = SCons.Node.Annotate
         SCons.Node.Annotate = my_annotate
@@ -1215,11 +1252,13 @@ class NodeTestCase(unittest.TestCase):
         try:
             self.node_string = '#1'
             n = SCons.Node.Node()
-            assert n.annotation == '#1', n.annotation
+            a = n.GetTag('annotation')
+            assert a == '#1', a
 
             self.node_string = '#2'
             n = SCons.Node.Node()
-            assert n.annotation == '#2', n.annotation
+            a = n.GetTag('annotation')
+            assert a == '#2', a
         finally:
             SCons.Node.Annotate = save_Annotate
 
@@ -1230,7 +1269,7 @@ class NodeTestCase(unittest.TestCase):
         n.set_state(3)
         n.binfo = 'xyz'
         n.includes = 'testincludes'
-        n.found_include = {'testkey':'testvalue'}
+        n.Tag('found_includes', {'testkey':'testvalue'})
         n.implicit = 'testimplicit'
 
         x = MyExecutor()
diff --git a/src/engine/SCons/Node/Python.py b/src/engine/SCons/Node/Python.py
index 3d8bdaa..f151fc5 100644
--- a/src/engine/SCons/Node/Python.py
+++ b/src/engine/SCons/Node/Python.py
@@ -32,15 +32,49 @@ __revision__ = "__FILE__ __REVISION__ __DATE__ __DEVELOPER__"
 import SCons.Node
 
 class ValueNodeInfo(SCons.Node.NodeInfoBase):
-    current_version_id = 1
+    __slots__ = ('csig',)
+    current_version_id = 2
 
     field_list = ['csig']
 
     def str_to_node(self, s):
         return Value(s)
 
+    def __getstate__(self):
+        """
+        Return all fields that shall be pickled. Walk the slots in the class
+        hierarchy and add those to the state dictionary. If a '__dict__' slot is
+        available, copy all entries to the dictionary. Also include the version
+        id, which is fixed for all instances of a class.
+        """
+        state = getattr(self, '__dict__', {}).copy()
+        for obj in type(self).mro():
+            for name in getattr(obj,'__slots__',()):
+                if hasattr(self, name):
+                    state[name] = getattr(self, name)
+
+        state['_version_id'] = self.current_version_id
+        try:
+            del state['__weakref__']
+        except KeyError:
+            pass
+        
+        return state
+
+    def __setstate__(self, state):
+        """
+        Restore the attributes from a pickled state.
+        """
+        # TODO check or discard version
+        del state['_version_id']
+        for key, value in state.items():
+            if key not in ('__weakref__',):
+                setattr(self, key, value)
+
+
 class ValueBuildInfo(SCons.Node.BuildInfoBase):
-    current_version_id = 1
+    __slots__ = ()
+    current_version_id = 2
 
 class Value(SCons.Node.Node):
     """A class for Python variables, typically passed on the command line 
@@ -53,6 +87,8 @@ class Value(SCons.Node.Node):
     def __init__(self, value, built_value=None):
         SCons.Node.Node.__init__(self)
         self.value = value
+        self.changed_since_last_build = 6
+        self.store_info = 0
         if built_value is not None:
             self.built_value = built_value
 
diff --git a/src/engine/SCons/Node/PythonTests.py b/src/engine/SCons/Node/PythonTests.py
index fcdfe77..e2e36bf 100644
--- a/src/engine/SCons/Node/PythonTests.py
+++ b/src/engine/SCons/Node/PythonTests.py
@@ -104,13 +104,13 @@ class ValueNodeInfoTestCase(unittest.TestCase):
     def test___init__(self):
         """Test ValueNodeInfo initialization"""
         vvv = SCons.Node.Python.Value('vvv')
-        ni = SCons.Node.Python.ValueNodeInfo(vvv)
+        ni = SCons.Node.Python.ValueNodeInfo()
 
 class ValueBuildInfoTestCase(unittest.TestCase):
     def test___init__(self):
         """Test ValueBuildInfo initialization"""
         vvv = SCons.Node.Python.Value('vvv')
-        bi = SCons.Node.Python.ValueBuildInfo(vvv)
+        bi = SCons.Node.Python.ValueBuildInfo()
 
 if __name__ == "__main__":
     suite = unittest.TestSuite()
diff --git a/src/engine/SCons/Node/__init__.py b/src/engine/SCons/Node/__init__.py
index 1f62971..f2d37c2 100644
--- a/src/engine/SCons/Node/__init__.py
+++ b/src/engine/SCons/Node/__init__.py
@@ -55,6 +55,8 @@ import SCons.Util
 
 from SCons.Debug import Trace
 
+print_duplicate = 0
+
 def classname(obj):
     return str(obj.__class__).split('.')[-1]
 
@@ -105,6 +107,233 @@ Annotate = do_nothing
 # clean builds and update runs (see release_target_info).
 interactive = False
 
+def is_derived_none(node):
+    raise NotImplementedError
+
+def is_derived_node(node):
+    """
+        Returns true if this node is derived (i.e. built).
+    """
+    return node.has_builder() or node.side_effect
+
+_is_derived_map = {0 : is_derived_none,
+                   1 : is_derived_node}
+
+def exists_none(node):
+    raise NotImplementedError
+
+def exists_always(node):
+    return 1
+
+def exists_base(node):
+    return node.stat() is not None
+
+def exists_entry(node):
+    """Return if the Entry exists.  Check the file system to see
+    what we should turn into first.  Assume a file if there's no
+    directory."""
+    node.disambiguate()
+    return _exists_map[node._func_exists](node)
+
+def exists_file(node):
+    # Duplicate from source path if we are set up to do this.
+    if node.duplicate and not node.is_derived() and not node.linked:
+        src = node.srcnode()
+        if src is not node:
+            # At this point, src is meant to be copied in a variant directory.
+            src = src.rfile()
+            if src.get_abspath() != node.get_abspath():
+                if src.exists():
+                    node.do_duplicate(src)
+                    # Can't return 1 here because the duplication might
+                    # not actually occur if the -n option is being used.
+                else:
+                    # The source file does not exist.  Make sure no old
+                    # copy remains in the variant directory.
+                    if print_duplicate:
+                        print "dup: no src for %s, unlinking old variant copy"%self
+                    if exists_base(node) or node.islink():
+                        node.fs.unlink(node.get_internal_path())
+                    # Return None explicitly because the Base.exists() call
+                    # above will have cached its value if the file existed.
+                    return None
+    return exists_base(node)
+
+_exists_map = {0 : exists_none,
+               1 : exists_always,
+               2 : exists_base,
+               3 : exists_entry,
+               4 : exists_file}
+
+
+def rexists_none(node):
+    raise NotImplementedError
+
+def rexists_node(node):
+    return node.exists()
+
+def rexists_base(node):
+    return node.rfile().exists()
+
+_rexists_map = {0 : rexists_none,
+                1 : rexists_node,
+                2 : rexists_base}
+
+def get_contents_none(node):
+    raise NotImplementedError
+
+def get_contents_entry(node):
+    """Fetch the contents of the entry.  Returns the exact binary
+    contents of the file."""
+    try:
+        node = node.disambiguate(must_exist=1)
+    except SCons.Errors.UserError:
+        # There was nothing on disk with which to disambiguate
+        # this entry.  Leave it as an Entry, but return a null
+        # string so calls to get_contents() in emitters and the
+        # like (e.g. in qt.py) don't have to disambiguate by hand
+        # or catch the exception.
+        return ''
+    else:
+        return _get_contents_map[node._func_get_contents](node)
+
+def get_contents_dir(node):
+    """Return content signatures and names of all our children
+    separated by new-lines. Ensure that the nodes are sorted."""
+    contents = []
+    for n in sorted(node.children(), key=lambda t: t.name):
+        contents.append('%s %s\n' % (n.get_csig(), n.name))
+    return ''.join(contents)
+
+def get_contents_file(node):    
+    if not node.rexists():
+        return ''
+    fname = node.rfile().get_abspath()
+    try:
+        contents = open(fname, "rb").read()
+    except EnvironmentError, e:
+        if not e.filename:
+            e.filename = fname
+        raise
+    return contents
+
+_get_contents_map = {0 : get_contents_none,
+                     1 : get_contents_entry,
+                     2 : get_contents_dir,
+                     3 : get_contents_file}
+
+def target_from_source_none(node, prefix, suffix, splitext):
+    raise NotImplementedError
+
+def target_from_source_base(node, prefix, suffix, splitext):
+    return node.dir.Entry(prefix + splitext(node.name)[0] + suffix)
+
+_target_from_source_map = {0 : target_from_source_none,
+                           1 : target_from_source_base}
+
+#
+# The new decider subsystem for Nodes
+#
+# We would set and overwrite the changed_since_last_build function
+# before, but for being able to use slots (less memory!) we now have
+# a dictionary of the different decider functions. Then in the Node
+# subclasses we simply store the index to the decider that should be
+# used by it.
+#
+
+#
+# First, the single decider functions
+#
+def changed_since_last_build_node(node, target, prev_ni):
+    """
+
+    Must be overridden in a specific subclass to return True if this
+    Node (a dependency) has changed since the last time it was used
+    to build the specified target.  prev_ni is this Node's state (for
+    example, its file timestamp, length, maybe content signature)
+    as of the last time the target was built.
+
+    Note that this method is called through the dependency, not the
+    target, because a dependency Node must be able to use its own
+    logic to decide if it changed.  For example, File Nodes need to
+    obey if we're configured to use timestamps, but Python Value Nodes
+    never use timestamps and always use the content.  If this method
+    were called through the target, then each Node's implementation
+    of this method would have to have more complicated logic to
+    handle all the different Node types on which it might depend.
+    """
+    raise NotImplementedError
+
+def changed_since_last_build_alias(node, target, prev_ni):
+    cur_csig = node.get_csig()
+    try:
+        return cur_csig != prev_ni.csig
+    except AttributeError:
+        return 1
+
+def changed_since_last_build_entry(node, target, prev_ni):
+    node.disambiguate()
+    return _decider_map[node.changed_since_last_build](node, target, prev_ni)
+
+def changed_since_last_build_state_changed(node, target, prev_ni):
+    return (node.state != SCons.Node.up_to_date)
+
+def decide_source(node, target, prev_ni):
+    return target.get_build_env().decide_source(node, target, prev_ni)
+
+def decide_target(node, target, prev_ni):
+    return target.get_build_env().decide_target(node, target, prev_ni)
+
+def changed_since_last_build_python(node, target, prev_ni):
+    cur_csig = node.get_csig()
+    try:
+        return cur_csig != prev_ni.csig
+    except AttributeError:
+        return 1
+
+
+#
+# Now, the mapping from indices to decider functions
+#
+_decider_map = {0 : changed_since_last_build_node,
+               1 : changed_since_last_build_alias,
+               2 : changed_since_last_build_entry,
+               3 : changed_since_last_build_state_changed,
+               4 : decide_source,
+               5 : decide_target,
+               6 : changed_since_last_build_python}
+
+do_store_info = True
+
+#
+# The new store_info subsystem for Nodes
+#
+# We would set and overwrite the store_info function
+# before, but for being able to use slots (less memory!) we now have
+# a dictionary of the different functions. Then in the Node
+# subclasses we simply store the index to the info method that should be
+# used by it.
+#
+
+#
+# First, the single info functions
+#
+
+def store_info_pass(node):
+    pass
+
+def store_info_file(node):
+    # Merge our build information into the already-stored entry.
+    # This accommodates "chained builds" where a file that's a target
+    # in one build (SConstruct file) is a source in a different build.
+    # See test/chained-build.py for the use case.
+    if do_store_info:
+        node.dir.sconsign().store_info(node.name, node)
+
+
+store_info_map = {0 : store_info_pass,
+                  1 : store_info_file}
+
 # Classes for signature info for Nodes.
 
 class NodeInfoBase(object):
@@ -114,11 +343,8 @@ class NodeInfoBase(object):
     Node subclasses should subclass NodeInfoBase to provide their own
     logic for dealing with their own Node-specific signature information.
     """
-    current_version_id = 1
-    def __init__(self, node=None):
-        # Create an object attribute from the class attribute so it ends up
-        # in the pickled data in the .sconsign file.
-        self._version_id = self.current_version_id
+    __slots__ = ('__weakref__',)
+    current_version_id = 2
     def update(self, node):
         try:
             field_list = self.field_list
@@ -138,13 +364,25 @@ class NodeInfoBase(object):
     def convert(self, node, val):
         pass
     def merge(self, other):
-        self.__dict__.update(other.__dict__)
+        """
+        Merge the fields of another object into this object. Already existing
+        information is overwritten by the other instance's data.
+        WARNING: If a '__dict__' slot is added, it should be updated instead of
+        replaced.
+        """
+        state = other.__getstate__()
+        self.__setstate__(state)
     def format(self, field_list=None, names=0):
         if field_list is None:
             try:
                 field_list = self.field_list
             except AttributeError:
-                field_list = sorted(self.__dict__.keys())
+                field_list = getattr(self, '__dict__', {}).keys()
+                for obj in type(self).mro():
+                    for slot in getattr(obj, '__slots__', ()):
+                        if slot not in ('__weakref__', '__dict__'):
+                            field_list.append(slot)
+                field_list.sort()
         fields = []
         for field in field_list:
             try:
@@ -157,6 +395,38 @@ class NodeInfoBase(object):
             fields.append(f)
         return fields
 
+    def __getstate__(self):
+        """
+        Return all fields that shall be pickled. Walk the slots in the class
+        hierarchy and add those to the state dictionary. If a '__dict__' slot is
+        available, copy all entries to the dictionary. Also include the version
+        id, which is fixed for all instances of a class.
+        """
+        state = getattr(self, '__dict__', {}).copy()
+        for obj in type(self).mro():
+            for name in getattr(obj,'__slots__',()):
+                if hasattr(self, name):
+                    state[name] = getattr(self, name)
+    
+        state['_version_id'] = self.current_version_id
+        try:
+            del state['__weakref__']
+        except KeyError:
+            pass
+        return state
+    
+    def __setstate__(self, state):
+        """
+        Restore the attributes from a pickled state. The version is discarded.
+        """
+        # TODO check or discard version
+        del state['_version_id']
+    
+        for key, value in state.items():
+            if key not in ('__weakref__',):
+                setattr(self, key, value)
+
+
 class BuildInfoBase(object):
     """
     The generic base class for build information for a Node.
@@ -167,30 +437,106 @@ class BuildInfoBase(object):
     generic build stuff we have to track:  sources, explicit dependencies,
     implicit dependencies, and action information.
     """
-    current_version_id = 1
-    def __init__(self, node=None):
+    __slots__ = ("bsourcesigs", "bdependsigs", "bimplicitsigs", "bactsig",
+                 "bsources", "bdepends", "bact", "bimplicit", "__weakref__")
+    current_version_id = 2
+    def __init__(self):
         # Create an object attribute from the class attribute so it ends up
         # in the pickled data in the .sconsign file.
-        self._version_id = self.current_version_id
         self.bsourcesigs = []
         self.bdependsigs = []
         self.bimplicitsigs = []
         self.bactsig = None
     def merge(self, other):
-        self.__dict__.update(other.__dict__)
+        """
+        Merge the fields of another object into this object. Already existing
+        information is overwritten by the other instance's data.
+        WARNING: If a '__dict__' slot is added, it should be updated instead of
+        replaced.
+        """
+        state = other.__getstate__()
+        self.__setstate__(state)
+ 
+    def __getstate__(self):
+        """
+        Return all fields that shall be pickled. Walk the slots in the class
+        hierarchy and add those to the state dictionary. If a '__dict__' slot is
+        available, copy all entries to the dictionary. Also include the version
+        id, which is fixed for all instances of a class.
+        """
+        state = getattr(self, '__dict__', {}).copy()
+        for obj in type(self).mro():
+            for name in getattr(obj,'__slots__',()):
+                if hasattr(self, name):
+                    state[name] = getattr(self, name)
+
+        state['_version_id'] = self.current_version_id
+        try:
+            del state['__weakref__']
+        except KeyError:
+            pass
+        return state
+
+    def __setstate__(self, state):
+        """
+        Restore the attributes from a pickled state.
+        """
+        # TODO check or discard version
+        del state['_version_id']
+        for key, value in state.items():
+            if key not in ('__weakref__',):
+                setattr(self, key, value)
 
 class Node(object):
     """The base Node class, for entities that we know how to
     build, or use to build other Nodes.
     """
 
-    if SCons.Memoize.use_memoizer:
-        __metaclass__ = SCons.Memoize.Memoized_Metaclass
-
-    memoizer_counters = []
+    __slots__ = ['sources',
+                 'sources_set',
+                 '_specific_sources',
+                 'depends',
+                 'depends_set',
+                 'ignore',
+                 'ignore_set',
+                 'prerequisites',
+                 'implicit',
+                 'waiting_parents',
+                 'waiting_s_e',
+                 'ref_count',
+                 'wkids',
+                 'env',
+                 'state',
+                 'precious',
+                 'noclean',
+                 'nocache',
+                 'cached',
+                 'always_build',
+                 'includes',
+                 'attributes',
+                 'side_effect',
+                 'side_effects',
+                 'linked',
+                 '_memo',
+                 'executor',
+                 'binfo',
+                 'ninfo',
+                 'builder',
+                 'is_explicit',
+                 'implicit_set',
+                 'changed_since_last_build',
+                 'store_info',
+                 'pseudo',
+                 '_tags',
+                 '_func_is_derived',
+                 '_func_exists',
+                 '_func_rexists',
+                 '_func_get_contents',
+                 '_func_target_from_source']
 
     class Attrs(object):
-        pass
+        __slots__ = ('shared', '__dict__')
+ 
 
     def __init__(self):
         if SCons.Debug.track_instances: logInstanceCreation(self, 'Node.Node')
@@ -234,7 +580,15 @@ class Node(object):
         self.side_effect = 0 # true iff this node is a side effect
         self.side_effects = [] # the side effects of building this target
         self.linked = 0 # is this node linked to the variant directory?
-
+        self.changed_since_last_build = 0
+        self.store_info = 0
+        self._tags = None
+        self._func_is_derived = 1
+        self._func_exists = 1
+        self._func_rexists = 1
+        self._func_get_contents = 0
+        self._func_target_from_source = 0
+        
         self.clear_memoized_values()
 
         # Let the interface in which the build engine is embedded
@@ -248,8 +602,7 @@ class Node(object):
     def get_suffix(self):
         return ''
 
-    memoizer_counters.append(SCons.Memoize.CountValue('get_build_env'))
-
+    @SCons.Memoize.CountMethodCall
     def get_build_env(self):
         """Fetch the appropriate Environment to build this node.
         """
@@ -418,7 +771,7 @@ class Node(object):
             pass
         else:
             self.ninfo.update(self)
-            self.store_info()
+            SCons.Node.store_info_map[self.store_info](self)
 
     def release_target_info(self):
         """Called just after this node has been marked
@@ -546,7 +899,7 @@ class Node(object):
         example: source with source builders are not derived in this sense,
         and hence should not return true.
         """
-        return self.has_builder() or self.side_effect
+        return _is_derived_map[self._func_is_derived](self)
 
     def alter_targets(self):
         """Return a list of alternate targets for this Node.
@@ -706,7 +1059,7 @@ class Node(object):
     BuildInfo = BuildInfoBase
 
     def new_ninfo(self):
-        ninfo = self.NodeInfo(self)
+        ninfo = self.NodeInfo()
         return ninfo
 
     def get_ninfo(self):
@@ -717,7 +1070,7 @@ class Node(object):
             return self.ninfo
 
     def new_binfo(self):
-        binfo = self.BuildInfo(self)
+        binfo = self.BuildInfo()
         return binfo
 
     def get_binfo(self):
@@ -802,14 +1155,6 @@ class Node(object):
     def get_cachedir_csig(self):
         return self.get_csig()
 
-    def store_info(self):
-        """Make the build signature permanent (that is, store it in the
-        .sconsign file or equivalent)."""
-        pass
-
-    def do_not_store_info(self):
-        pass
-
     def get_stored_info(self):
         return None
 
@@ -847,13 +1192,16 @@ class Node(object):
 
     def exists(self):
         """Does this node exists?"""
-        # All node exist by default:
-        return 1
+        return _exists_map[self._func_exists](self)
 
     def rexists(self):
         """Does this node exist locally or in a repositiory?"""
         # There are no repositories by default:
-        return self.exists()
+        return _rexists_map[self._func_rexists](self)
+
+    def get_contents(self):
+        """Fetch the contents of the entry."""
+        return _get_contents_map[self._func_get_contents](self)
 
     def missing(self):
         return not self.is_derived() and \
@@ -941,11 +1289,10 @@ class Node(object):
         # build info that it's cached so we can re-calculate it.
         self.executor_cleanup()
 
-    memoizer_counters.append(SCons.Memoize.CountValue('_children_get'))
-
+    @SCons.Memoize.CountMethodCall
     def _children_get(self):
         try:
-            return self._memo['children_get']
+            return self._memo['_children_get']
         except KeyError:
             pass
 
@@ -976,7 +1323,7 @@ class Node(object):
         else:
             children = self.all_children(scan=0)
 
-        self._memo['children_get'] = children
+        self._memo['_children_get'] = children
         return children
 
     def all_children(self, scan=1):
@@ -1016,9 +1363,6 @@ class Node(object):
     def get_state(self):
         return self.state
 
-    def state_has_changed(self, target, prev_ni):
-        return (self.state != SCons.Node.up_to_date)
-
     def get_env(self):
         env = self.env
         if not env:
@@ -1026,28 +1370,28 @@ class Node(object):
             env = SCons.Defaults.DefaultEnvironment()
         return env
 
-    def changed_since_last_build(self, target, prev_ni):
-        """
-
-        Must be overridden in a specific subclass to return True if this
-        Node (a dependency) has changed since the last time it was used
-        to build the specified target.  prev_ni is this Node's state (for
-        example, its file timestamp, length, maybe content signature)
-        as of the last time the target was built.
-
-        Note that this method is called through the dependency, not the
-        target, because a dependency Node must be able to use its own
-        logic to decide if it changed.  For example, File Nodes need to
-        obey if we're configured to use timestamps, but Python Value Nodes
-        never use timestamps and always use the content.  If this method
-        were called through the target, then each Node's implementation
-        of this method would have to have more complicated logic to
-        handle all the different Node types on which it might depend.
-        """
-        raise NotImplementedError
-
     def Decider(self, function):
-        SCons.Util.AddMethod(self, function, 'changed_since_last_build')
+        foundkey = None
+        for k, v in _decider_map.iteritems():
+            if v == function:
+                foundkey = k
+                break
+        if not foundkey:
+            foundkey = len(_decider_map)
+            _decider_map[foundkey] = function
+        self.changed_since_last_build = foundkey
+
+    def Tag(self, key, value):
+        """ Add a user-defined tag. """
+        if not self._tags:
+            self._tags = {}
+        self._tags[key] = value
+
+    def GetTag(self, key):
+        """ Return a user-defined tag. """
+        if not self._tags:
+            return None
+        return self._tags.get(key, None)
 
     def changed(self, node=None, allowcache=False):
         """
@@ -1095,7 +1439,7 @@ class Node(object):
             result = True
 
         for child, prev_ni in zip(children, then):
-            if child.changed_since_last_build(self, prev_ni):
+            if _decider_map[child.changed_since_last_build](child, self, prev_ni):
                 if t: Trace(': %s changed' % child)
                 result = True
 
@@ -1266,7 +1610,7 @@ class Node(object):
         for k in new_bkids:
             if not k in old_bkids:
                 lines.append("`%s' is a new dependency\n" % stringify(k))
-            elif k.changed_since_last_build(self, osig[k]):
+            elif _decider_map[k.changed_since_last_build](k, self, osig[k]):
                 lines.append("`%s' changed\n" % stringify(k))
 
         if len(lines) == 0 and old_bkids != new_bkids:
diff --git a/src/engine/SCons/PathList.py b/src/engine/SCons/PathList.py
index f3de57c..350e1ac 100644
--- a/src/engine/SCons/PathList.py
+++ b/src/engine/SCons/PathList.py
@@ -171,11 +171,6 @@ class PathListCache(object):
     cheaply avoid re-parsing both values of CPPPATH by using the
     common value from this cache.
     """
-    if SCons.Memoize.use_memoizer:
-        __metaclass__ = SCons.Memoize.Memoized_Metaclass
-
-    memoizer_counters = []
-
     def __init__(self):
         self._memo = {}
 
@@ -196,8 +191,7 @@ class PathListCache(object):
             pathlist = tuple(SCons.Util.flatten(pathlist))
         return pathlist
 
-    memoizer_counters.append(SCons.Memoize.CountDict('PathList', _PathList_key))
-
+    @SCons.Memoize.CountDictCall(_PathList_key)
     def PathList(self, pathlist):
         """
         Returns the cached _PathList object for the specified pathlist,
diff --git a/src/engine/SCons/SConf.py b/src/engine/SCons/SConf.py
index 87432ef..8bce8ce 100644
--- a/src/engine/SCons/SConf.py
+++ b/src/engine/SCons/SConf.py
@@ -175,8 +175,11 @@ class SConfBuildInfo(SCons.Node.FS.FileBuildInfo):
     are result (did the builder succeed last time?) and string, which
     contains messages of the original build phase.
     """
-    result = None # -> 0/None -> no error, != 0 error
-    string = None # the stdout / stderr output when building the target
+    __slots__ = ('result', 'string')
+    
+    def __init__(self):
+        self.result = None # -> 0/None -> no error, != 0 error
+        self.string = None # the stdout / stderr output when building the target
 
     def set_build_result(self, result, string):
         self.result = result
@@ -352,8 +355,10 @@ class SConfBuildTask(SCons.Taskmaster.AlwaysTask):
                 raise SCons.Errors.ExplicitExit(self.targets[0],exc_value.code)
             except Exception, e:
                 for t in self.targets:
-                    binfo = t.get_binfo()
-                    binfo.__class__ = SConfBuildInfo
+                    #binfo = t.get_binfo()
+                    #binfo.__class__ = SConfBuildInfo
+                    binfo = SConfBuildInfo()
+                    binfo.merge(t.get_binfo())
                     binfo.set_build_result(1, s.getvalue())
                     sconsign_entry = SCons.SConsign.SConsignEntry()
                     sconsign_entry.binfo = binfo
@@ -370,8 +375,10 @@ class SConfBuildTask(SCons.Taskmaster.AlwaysTask):
                 raise e
             else:
                 for t in self.targets:
-                    binfo = t.get_binfo()
-                    binfo.__class__ = SConfBuildInfo
+                    #binfo = t.get_binfo()
+                    #binfo.__class__ = SConfBuildInfo
+                    binfo = SConfBuildInfo()
+                    binfo.merge(t.get_binfo())
                     binfo.set_build_result(0, s.getvalue())
                     sconsign_entry = SCons.SConsign.SConsignEntry()
                     sconsign_entry.binfo = binfo
@@ -500,7 +507,7 @@ class SConfBase(object):
         # we override the store_info() method with a null place-holder
         # so we really control how it gets written.
         for n in nodes:
-            n.store_info = n.do_not_store_info
+            n.store_info = 0
             if not hasattr(n, 'attributes'):
                 n.attributes = SCons.Node.Node.Attrs()
             n.attributes.keep_targetinfo = 1
@@ -640,7 +647,7 @@ class SConfBase(object):
         ok = self.TryLink(text, extension)
         if( ok ):
             prog = self.lastTarget
-            pname = prog.path
+            pname = prog.get_internal_path()
             output = self.confdir.File(os.path.basename(pname)+'.out')
             node = self.env.Command(output, prog, [ [ pname, ">", "${TARGET}"] ])
             ok = self.BuildNodes(node)
@@ -684,7 +691,6 @@ class SConfBase(object):
         else:
             if not os.path.isdir( dirName ):
                 os.makedirs( dirName )
-                node._exists = 1
 
     def _startup(self):
         """Private method. Set up logstream, and set the environment
diff --git a/src/engine/SCons/SConfTests.py b/src/engine/SCons/SConfTests.py
index 1c4b401..233ee78 100644
--- a/src/engine/SCons/SConfTests.py
+++ b/src/engine/SCons/SConfTests.py
@@ -221,8 +221,6 @@ class SConfTestCase(unittest.TestCase):
                         pass
                     def get_stored_info(self):
                         pass
-                    def do_not_store_info(self):
-                        pass
                     def get_executor(self):
                         class Executor(object):
                             def __init__(self, targets):
diff --git a/src/engine/SCons/SConsign.py b/src/engine/SCons/SConsign.py
index 6555fcb..74ee804 100644
--- a/src/engine/SCons/SConsign.py
+++ b/src/engine/SCons/SConsign.py
@@ -122,16 +122,40 @@ class SConsignEntry(object):
     XXX As coded below, we do expect a '.binfo' attribute to be added,
     but we'll probably generalize this in the next refactorings.
     """
-    current_version_id = 1
+    __slots__ = ("binfo", "ninfo", "__weakref__")
+    current_version_id = 2
+    
     def __init__(self):
         # Create an object attribute from the class attribute so it ends up
         # in the pickled data in the .sconsign file.
-        _version_id = self.current_version_id
+        #_version_id = self.current_version_id
+        pass
+    
     def convert_to_sconsign(self):
         self.binfo.convert_to_sconsign()
+        
     def convert_from_sconsign(self, dir, name):
         self.binfo.convert_from_sconsign(dir, name)
 
+    def __getstate__(self):
+        state = getattr(self, '__dict__', {}).copy()
+        for obj in type(self).mro():
+            for name in getattr(obj,'__slots__',()):
+                if hasattr(self, name):
+                    state[name] = getattr(self, name)
+
+        state['_version_id'] = self.current_version_id
+        try:
+            del state['__weakref__']
+        except KeyError:
+            pass
+        return state
+
+    def __setstate__(self, state):
+        for key, value in state.items():
+            if key not in ('_version_id','__weakref__'):
+                setattr(self, key, value)
+        
 class Base(object):
     """
     This is the controlling class for the signatures for the collection of
@@ -202,7 +226,7 @@ class DB(Base):
         # Read using the path relative to the top of the Repository
         # (self.dir.tpath) from which we're fetching the signature
         # information.
-        path = normcase(dir.tpath)
+        path = normcase(dir.get_tpath())
         try:
             rawentries = db[path]
         except KeyError:
@@ -217,7 +241,7 @@ class DB(Base):
                 raise
             except Exception, e:
                 SCons.Warnings.warn(SCons.Warnings.CorruptSConsignWarning,
-                                    "Ignoring corrupt sconsign entry : %s (%s)\n"%(self.dir.tpath, e))
+                                    "Ignoring corrupt sconsign entry : %s (%s)\n"%(self.dir.get_tpath(), e))
             for key, entry in self.entries.items():
                 entry.convert_from_sconsign(dir, key)
 
@@ -244,7 +268,7 @@ class DB(Base):
         # directory (self.dir.path), not relative to the top of
         # the Repository; we only write to our own .sconsign file,
         # not to .sconsign files in Repositories.
-        path = normcase(self.dir.path)
+        path = normcase(self.dir.get_internal_path())
         for key, entry in self.entries.items():
             entry.convert_to_sconsign()
         db[path] = pickle.dumps(self.entries, 1)
@@ -287,7 +311,7 @@ class DirFile(Dir):
         """
 
         self.dir = dir
-        self.sconsign = os.path.join(dir.path, '.sconsign')
+        self.sconsign = os.path.join(dir.get_internal_path(), '.sconsign')
 
         try:
             fp = open(self.sconsign, 'rb')
@@ -323,7 +347,7 @@ class DirFile(Dir):
 
         self.merge()
 
-        temp = os.path.join(self.dir.path, '.scons%d' % os.getpid())
+        temp = os.path.join(self.dir.get_internal_path(), '.scons%d' % os.getpid())
         try:
             file = open(temp, 'wb')
             fname = temp
diff --git a/src/engine/SCons/SConsignTests.py b/src/engine/SCons/SConsignTests.py
index f71e53e..d40a7b6 100644
--- a/src/engine/SCons/SConsignTests.py
+++ b/src/engine/SCons/SConsignTests.py
@@ -62,6 +62,10 @@ class DummyNode(object):
         return self.binfo
     def get_binfo(self):
         return self.binfo
+    def get_internal_path(self):
+        return self.path
+    def get_tpath(self):
+        return self.tpath
 
 class SConsignTestCase(unittest.TestCase):
     def setUp(self):
diff --git a/src/engine/SCons/Scanner/CTests.py b/src/engine/SCons/Scanner/CTests.py
index 6418754..9c7df12 100644
--- a/src/engine/SCons/Scanner/CTests.py
+++ b/src/engine/SCons/Scanner/CTests.py
@@ -270,17 +270,18 @@ class CScannerTestCase5(unittest.TestCase):
         path = s.path(env)
 
         n = env.File('f3.cpp')
-        def my_rexists(s=n):
-            s.rexists_called = 1
-            return s.old_rexists()
-        setattr(n, 'old_rexists', n.rexists)
-        setattr(n, 'rexists', my_rexists)
+        def my_rexists(s):
+            s.Tag('rexists_called', 1)
+            return SCons.Node._rexists_map[s.GetTag('old_rexists')](s)
+        n.Tag('old_rexists', n._func_rexists)
+        SCons.Node._rexists_map[3] = my_rexists
+        n._func_rexists = 3
 
         deps = s(n, env, path)
 
         # Make sure rexists() got called on the file node being
         # scanned, essential for cooperation with VariantDir functionality.
-        assert n.rexists_called
+        assert n.GetTag('rexists_called')
         
         headers =  ['f1.h', 'f2.h', 'f3-test.h',
                     'd1/f1.h', 'd1/f2.h', 'd1/f3-test.h']
diff --git a/src/engine/SCons/Scanner/Dir.py b/src/engine/SCons/Scanner/Dir.py
index 1cecfb7..cbfb6fb 100644
--- a/src/engine/SCons/Scanner/Dir.py
+++ b/src/engine/SCons/Scanner/Dir.py
@@ -77,7 +77,7 @@ def scan_on_disk(node, env, path=()):
     that and then call the in-memory scanning function.
     """
     try:
-        flist = node.fs.listdir(node.abspath)
+        flist = node.fs.listdir(node.get_abspath())
     except (IOError, OSError):
         return []
     e = node.Entry
diff --git a/src/engine/SCons/Scanner/FortranTests.py b/src/engine/SCons/Scanner/FortranTests.py
index 252da64..aaefa79 100644
--- a/src/engine/SCons/Scanner/FortranTests.py
+++ b/src/engine/SCons/Scanner/FortranTests.py
@@ -356,17 +356,18 @@ class FortranScannerTestCase9(unittest.TestCase):
         path = s.path(env)
 
         n = env.File('fff3.f')
-        def my_rexists(s=n):
-            s.rexists_called = 1
-            return s.old_rexists()
-        setattr(n, 'old_rexists', n.rexists)
-        setattr(n, 'rexists', my_rexists)
+        def my_rexists(s):
+            s.Tag('rexists_called', 1)
+            return SCons.Node._rexists_map[s.GetTag('old_rexists')](s)
+        n.Tag('old_rexists', n._func_rexists)
+        SCons.Node._rexists_map[3] = my_rexists
+        n._func_rexists = 3
 
         deps = s(n, env, path)
 
         # Make sure rexists() got called on the file node being
         # scanned, essential for cooperation with VariantDir functionality.
-        assert n.rexists_called
+        assert n.GetTag('rexists_called')
 
         headers =  ['d1/f3.f', 'f3.f']
         deps_match(self, deps, headers)
diff --git a/src/engine/SCons/Scanner/IDLTests.py b/src/engine/SCons/Scanner/IDLTests.py
index 675c70c..227799e 100644
--- a/src/engine/SCons/Scanner/IDLTests.py
+++ b/src/engine/SCons/Scanner/IDLTests.py
@@ -290,17 +290,18 @@ class IDLScannerTestCase5(unittest.TestCase):
         path = s.path(env)
 
         n = env.File('t3.idl')
-        def my_rexists(s=n):
-            s.rexists_called = 1
-            return s.old_rexists()
-        setattr(n, 'old_rexists', n.rexists)
-        setattr(n, 'rexists', my_rexists)
+        def my_rexists(s):
+            s.Tag('rexists_called', 1)
+            return SCons.Node._rexists_map[s.GetTag('old_rexists')](s)
+        n.Tag('old_rexists', n._func_rexists)
+        SCons.Node._rexists_map[3] = my_rexists
+        n._func_rexists = 3
 
         deps = s(n, env, path)
 
         # Make sure rexists() got called on the file node being
         # scanned, essential for cooperation with VariantDir functionality.
-        assert n.rexists_called
+        assert n.GetTag('rexists_called')
         
         headers =  ['d1/f1.idl', 'd1/f2.idl',
                     'f1.idl', 'f2.idl', 'f3-test.idl',
diff --git a/src/engine/SCons/Script/Main.py b/src/engine/SCons/Script/Main.py
index c7a9d27..323fba9 100644
--- a/src/engine/SCons/Script/Main.py
+++ b/src/engine/SCons/Script/Main.py
@@ -214,7 +214,7 @@ class BuildTask(SCons.Taskmaster.OutOfDateTask):
         if self.top and not t.has_builder() and not t.side_effect:
             if not t.exists():
                 if t.__class__.__name__ in ('File', 'Dir', 'Entry'):
-                    errstr="Do not know how to make %s target `%s' (%s)." % (t.__class__.__name__, t, t.abspath)
+                    errstr="Do not know how to make %s target `%s' (%s)." % (t.__class__.__name__, t, t.get_abspath())
                 else: # Alias or Python or ...
                     errstr="Do not know how to make %s target `%s'." % (t.__class__.__name__, t)
                 sys.stderr.write("scons: *** " + errstr)
@@ -351,7 +351,7 @@ class CleanTask(SCons.Taskmaster.AlwaysTask):
         if target in SCons.Environment.CleanTargets:
             files = SCons.Environment.CleanTargets[target]
             for f in files:
-                self.fs_delete(f.abspath, str(f), remove)
+                self.fs_delete(f.get_abspath(), str(f), remove)
 
     def show(self):
         for t in self._get_files_to_clean():
@@ -672,7 +672,7 @@ def _set_debug_values(options):
     if "prepare" in debug_values:
         SCons.Taskmaster.print_prepare = 1
     if "duplicate" in debug_values:
-        SCons.Node.FS.print_duplicate = 1
+        SCons.Node.print_duplicate = 1
 
 def _create_path(plist):
     path = '.'
@@ -946,9 +946,9 @@ def _main(parser):
         progress_display.set_mode(0)
 
     if options.site_dir:
-        _load_site_scons_dir(d.path, options.site_dir)
+        _load_site_scons_dir(d.get_internal_path(), options.site_dir)
     elif not options.no_site_dir:
-        _load_all_site_scons_dirs(d.path)
+        _load_all_site_scons_dirs(d.get_internal_path())
 
     if options.include_dir:
         sys.path = options.include_dir + sys.path
@@ -1111,7 +1111,6 @@ def _build_targets(fs, options, targets, target_top):
     display.set_mode(not options.silent)
     SCons.Action.print_actions          = not options.silent
     SCons.Action.execute_actions        = not options.no_exec
-    SCons.Node.FS.do_store_info         = not options.no_exec
     SCons.Node.do_store_info            = not options.no_exec
     SCons.SConf.dryrun                  = options.no_exec
 
diff --git a/src/engine/SCons/Script/SConscript.py b/src/engine/SCons/Script/SConscript.py
index f4a7f07..0a5720d 100644
--- a/src/engine/SCons/Script/SConscript.py
+++ b/src/engine/SCons/Script/SConscript.py
@@ -265,7 +265,7 @@ def _SConscript(fs, *files, **kw):
                             call_stack[-1].globals.update({__file__:old_file})
                 else:
                     SCons.Warnings.warn(SCons.Warnings.MissingSConscriptWarning,
-                             "Ignoring missing SConscript '%s'" % f.path)
+                             "Ignoring missing SConscript '%s'" % f.get_internal_path())
 
         finally:
             SCons.Script.sconscript_reading = SCons.Script.sconscript_reading - 1
@@ -438,7 +438,7 @@ class SConsEnvironment(SCons.Environment.Base):
                     fname = fn.get_path(src_dir)
                     files = [os.path.join(str(variant_dir), fname)]
                 else:
-                    files = [fn.abspath]
+                    files = [fn.get_abspath()]
                 kw['src_dir'] = variant_dir
             self.fs.VariantDir(variant_dir, src_dir, duplicate)
 
diff --git a/src/engine/SCons/Taskmaster.py b/src/engine/SCons/Taskmaster.py
index 5de1cda..345534e 100644
--- a/src/engine/SCons/Taskmaster.py
+++ b/src/engine/SCons/Taskmaster.py
@@ -242,7 +242,7 @@ class Task(object):
                 #
                 for t in cached_targets:
                     try:
-                        t.fs.unlink(t.path)
+                        t.fs.unlink(t.get_internal_path())
                     except (IOError, OSError):
                         pass
                 self.targets[0].build()
diff --git a/src/engine/SCons/Tool/__init__.py b/src/engine/SCons/Tool/__init__.py
index 2621cf9..efd2e33 100644
--- a/src/engine/SCons/Tool/__init__.py
+++ b/src/engine/SCons/Tool/__init__.py
@@ -340,7 +340,7 @@ symlinks for the platform we are on"""
 
     if version:
         # here we need the full pathname so the links end up in the right directory
-        libname = getattr(target[0].attributes, 'shlibpath', target[0].path)
+        libname = getattr(target[0].attributes, 'shlibpath', target[0].get_internal_path())
         if Verbose:
             print "VerShLib: target lib is = ", libname
             print "VerShLib: name is = ", target[0].name
diff --git a/src/engine/SCons/Tool/docbook/__init__.py b/src/engine/SCons/Tool/docbook/__init__.py
index 26a1a95..aead43c 100644
--- a/src/engine/SCons/Tool/docbook/__init__.py
+++ b/src/engine/SCons/Tool/docbook/__init__.py
@@ -448,7 +448,7 @@ def DocbookEpub(env, target, source=None, *args, **kw):
         Ensure all the resources in the manifest are present in the OEBPS directory.
         """
         hrefs = []
-        content_file = os.path.join(source[0].abspath, 'content.opf')
+        content_file = os.path.join(source[0].get_abspath(), 'content.opf')
         if not os.path.isfile(content_file):
             return
         
@@ -491,9 +491,9 @@ def DocbookEpub(env, target, source=None, *args, **kw):
         for href in hrefs:
             # If the resource was not already created by DocBook XSL itself, 
             # copy it into the OEBPS folder
-            referenced_file = os.path.join(source[0].abspath, href)
+            referenced_file = os.path.join(source[0].get_abspath(), href)
             if not os.path.exists(referenced_file):
-                shutil.copy(href, os.path.join(source[0].abspath, href))
+                shutil.copy(href, os.path.join(source[0].get_abspath(), href))
         
     # Init list of targets/sources
     target, source = __extend_targets_sources(target, source)
diff --git a/src/engine/SCons/Tool/mslink.py b/src/engine/SCons/Tool/mslink.py
index 37af34e..69baa43 100644
--- a/src/engine/SCons/Tool/mslink.py
+++ b/src/engine/SCons/Tool/mslink.py
@@ -208,7 +208,7 @@ def embedManifestDllCheck(target, source, env):
     """Function run by embedManifestDllCheckAction to check for existence of manifest
     and other conditions, and embed the manifest by calling embedManifestDllAction if so."""
     if env.get('WINDOWS_EMBED_MANIFEST', 0):
-        manifestSrc = target[0].abspath + '.manifest'
+        manifestSrc = target[0].get_abspath() + '.manifest'
         if os.path.exists(manifestSrc):
             ret = (embedManifestDllAction) ([target[0]],None,env)        
             if ret:
@@ -222,7 +222,7 @@ def embedManifestExeCheck(target, source, env):
     """Function run by embedManifestExeCheckAction to check for existence of manifest
     and other conditions, and embed the manifest by calling embedManifestExeAction if so."""
     if env.get('WINDOWS_EMBED_MANIFEST', 0):
-        manifestSrc = target[0].abspath + '.manifest'
+        manifestSrc = target[0].get_abspath() + '.manifest'
         if os.path.exists(manifestSrc):
             ret = (embedManifestExeAction) ([target[0]],None,env)
             if ret:
diff --git a/src/engine/SCons/Tool/packaging/__init__.py b/src/engine/SCons/Tool/packaging/__init__.py
index 95311a2..1a979ab 100644
--- a/src/engine/SCons/Tool/packaging/__init__.py
+++ b/src/engine/SCons/Tool/packaging/__init__.py
@@ -80,7 +80,7 @@ def Tag(env, target, source, *more_tags, **kw_tags):
             #if not k.startswith('PACKAGING_'):
             if k[:10] != 'PACKAGING_':
                 k='PACKAGING_'+k
-            setattr(t, k, v)
+            t.Tag(k, v)
 
 def Package(env, target=None, source=None, **kw):
     """ Entry point for the package tool.
@@ -235,9 +235,11 @@ def copy_attr(f1, f2):
     #pattrs = [x for x in dir(f1) if not hasattr(f2, x) and\
     #                                x.startswith('PACKAGING_')]
     copyit = lambda x: not hasattr(f2, x) and x[:10] == 'PACKAGING_'
-    pattrs = list(filter(copyit, dir(f1)))
-    for attr in pattrs:
-        setattr(f2, attr, getattr(f1, attr))
+    if f1._tags:
+        pattrs = list(filter(copyit, f1._tags))
+        for attr in pattrs:
+            f2.Tag(attr, f1.GetTag(attr))
+
 def putintopackageroot(target, source, env, pkgroot, honor_install_location=1):
     """ Uses the CopyAs builder to copy all source files to the directory given
     in pkgroot.
@@ -262,9 +264,9 @@ def putintopackageroot(target, source, env, pkgroot, honor_install_location=1):
         if file.is_under(pkgroot):
             new_source.append(file)
         else:
-            if hasattr(file, 'PACKAGING_INSTALL_LOCATION') and\
+            if file.GetTag('PACKAGING_INSTALL_LOCATION') and\
                        honor_install_location:
-                new_name=make_path_relative(file.PACKAGING_INSTALL_LOCATION)
+                new_name=make_path_relative(file.GetTag('PACKAGING_INSTALL_LOCATION'))
             else:
                 new_name=make_path_relative(file.get_path())
 
@@ -301,7 +303,7 @@ def stripinstallbuilder(target, source, env):
             for ss in s.sources:
                 n_source.append(ss)
                 copy_attr(s, ss)
-                setattr(ss, 'PACKAGING_INSTALL_LOCATION', s.get_path())
+                ss.Tag('PACKAGING_INSTALL_LOCATION', s.get_path())
 
     return (target, n_source)
 
diff --git a/src/engine/SCons/Tool/packaging/ipk.py b/src/engine/SCons/Tool/packaging/ipk.py
index 6549445..84f4e20 100644
--- a/src/engine/SCons/Tool/packaging/ipk.py
+++ b/src/engine/SCons/Tool/packaging/ipk.py
@@ -120,7 +120,7 @@ def build_specfiles(source, target, env):
             return opened_files[needle]
         except KeyError:
             file=filter(lambda x: x.get_path().rfind(needle)!=-1, haystack)[0]
-            opened_files[needle]=open(file.abspath, 'w')
+            opened_files[needle]=open(file.get_abspath(), 'w')
             return opened_files[needle]
 
     control_file=open_file('control', target)
diff --git a/src/engine/SCons/Tool/packaging/msi.py b/src/engine/SCons/Tool/packaging/msi.py
index fe78c9c..172038f 100644
--- a/src/engine/SCons/Tool/packaging/msi.py
+++ b/src/engine/SCons/Tool/packaging/msi.py
@@ -189,7 +189,7 @@ def build_wxsfile(target, source, env):
     """ compiles a .wxs file from the keywords given in env['msi_spec'] and
         by analyzing the tree of source nodes and their tags.
     """
-    file = open(target[0].abspath, 'w')
+    file = open(target[0].get_abspath(), 'w')
 
     try:
         # Create a document with the Wix root tag
diff --git a/src/engine/SCons/Tool/packaging/rpm.py b/src/engine/SCons/Tool/packaging/rpm.py
index 2bc3063..656d8fb 100644
--- a/src/engine/SCons/Tool/packaging/rpm.py
+++ b/src/engine/SCons/Tool/packaging/rpm.py
@@ -130,8 +130,7 @@ def build_specfile(target, source, env):
     """ Builds a RPM specfile from a dictionary with string metadata and
     by analyzing a tree of nodes.
     """
-    file = open(target[0].abspath, 'w')
-    str  = ""
+    file = open(target[0].get_abspath(), 'w')
 
     try:
         file.write( build_specfile_header(env) )
@@ -279,7 +278,9 @@ def build_specfile_filesection(spec, files):
         tags = {}
         for k in supported_tags.keys():
             try:
-                tags[k]=getattr(file, k)
+                v = file.GetTag(k)
+                if v:
+                    tags[k] = v
             except AttributeError:
                 pass
 
@@ -287,7 +288,7 @@ def build_specfile_filesection(spec, files):
         str = str + SimpleTagCompiler(supported_tags, mandatory=0).compile( tags )
 
         str = str + ' '
-        str = str + file.PACKAGING_INSTALL_LOCATION
+        str = str + file.GetTag('PACKAGING_INSTALL_LOCATION')
         str = str + '\n\n'
 
     return str
diff --git a/src/engine/SCons/Tool/rpm.py b/src/engine/SCons/Tool/rpm.py
index 1f6eafe..b7d65a8 100644
--- a/src/engine/SCons/Tool/rpm.py
+++ b/src/engine/SCons/Tool/rpm.py
@@ -51,11 +51,11 @@ def get_cmd(source, env):
     if SCons.Util.is_List(source):
         tar_file_with_included_specfile = source[0]
     return "%s %s %s"%(env['RPM'], env['RPMFLAGS'],
-                       tar_file_with_included_specfile.abspath )
+                       tar_file_with_included_specfile.get_abspath() )
 
 def build_rpm(target, source, env):
     # create a temporary rpm build root.
-    tmpdir = os.path.join( os.path.dirname( target[0].abspath ), 'rpmtemp' )
+    tmpdir = os.path.join( os.path.dirname( target[0].get_abspath() ), 'rpmtemp' )
     if os.path.exists(tmpdir):
         shutil.rmtree(tmpdir)
 
@@ -87,7 +87,7 @@ def build_rpm(target, source, env):
             expected   = os.path.basename(input.get_path())
 
             assert expected == rpm_output, "got %s but expected %s" % (rpm_output, expected)
-            shutil.copy( output, input.abspath )
+            shutil.copy( output, input.get_abspath() )
 
 
     # cleanup before leaving.
diff --git a/src/engine/SCons/Tool/swig.py b/src/engine/SCons/Tool/swig.py
index f166174..a315182 100644
--- a/src/engine/SCons/Tool/swig.py
+++ b/src/engine/SCons/Tool/swig.py
@@ -42,6 +42,7 @@ import SCons.Defaults
 import SCons.Scanner
 import SCons.Tool
 import SCons.Util
+import SCons.Node
 
 SwigAction = SCons.Action.Action('$SWIGCOM', '$SWIGCOMSTR')
 
@@ -117,9 +118,13 @@ def _swigEmitter(target, source, env):
             if outdir:
                  java_files = [os.path.join(outdir, j) for j in java_files]
             java_files = list(map(env.fs.File, java_files))
+            def t_from_s(t, p, s, x):
+                return t.dir
+            tsm = SCons.Node._target_from_source_map
+            tkey = len(tsm)
+            tsm[tkey] = t_from_s
             for jf in java_files:
-                t_from_s = lambda t, p, s, x: t.dir
-                SCons.Util.AddMethod(jf, t_from_s, 'target_from_source')
+                jf._func_target_from_source = tkey
             target.extend(java_files)
     return (target, source)
 
diff --git a/src/engine/SCons/Util.py b/src/engine/SCons/Util.py
index 822d524..4890ba2 100644
--- a/src/engine/SCons/Util.py
+++ b/src/engine/SCons/Util.py
@@ -992,7 +992,7 @@ class Selector(OrderedDict):
     def __call__(self, env, source, ext=None):
         if ext is None:
             try:
-                ext = source[0].suffix
+                ext = source[0].get_suffix()
             except IndexError:
                 ext = ""
         try:
diff --git a/src/engine/SCons/UtilTests.py b/src/engine/SCons/UtilTests.py
index b0c15c5..795bc46 100644
--- a/src/engine/SCons/UtilTests.py
+++ b/src/engine/SCons/UtilTests.py
@@ -591,10 +591,11 @@ class UtilTestCase(unittest.TestCase):
         class MyNode(object):
             def __init__(self, name):
                 self.name = name
-                self.suffix = os.path.splitext(name)[1]
 
             def __str__(self):
                 return self.name
+            def get_suffix(self):
+                return os.path.splitext(self.name)[1]
 
         s = Selector({'a' : 'AAA', 'b' : 'BBB'})
         assert s['a'] == 'AAA', s['a']
diff --git a/src/script/sconsign.py b/src/script/sconsign.py
index e5e9d4f..ef32a93 100644
--- a/src/script/sconsign.py
+++ b/src/script/sconsign.py
@@ -278,7 +278,7 @@ def field(name, entry, verbose=Verbose):
 def nodeinfo_raw(name, ninfo, prefix=""):
     # This just formats the dictionary, which we would normally use str()
     # to do, except that we want the keys sorted for deterministic output.
-    d = ninfo.__dict__
+    d = ninfo.__getstate__()
     try:
         keys = ninfo.field_list + ['_version_id']
     except AttributeError:
diff --git a/test/Actions/addpost-link.py b/test/Actions/addpost-link.py
index a148051..04cd68d 100644
--- a/test/Actions/addpost-link.py
+++ b/test/Actions/addpost-link.py
@@ -54,7 +54,7 @@ myprog = env.Program('test1.c',
                      OBJSUFFIX = '.obj',
                      PROGSUFFIX = '.exe')
 if ARGUMENTS['case']=='2':
-  AddPostAction(myprog, Action(r'%(_python_)s strip.py ' + myprog[0].abspath))
+  AddPostAction(myprog, Action(r'%(_python_)s strip.py ' + myprog[0].get_abspath()))
 """ % locals())
 
 test.write('test1.c', """\
diff --git a/test/CacheDir/NoCache.py b/test/CacheDir/NoCache.py
index 7e9b540..b035b44 100644
--- a/test/CacheDir/NoCache.py
+++ b/test/CacheDir/NoCache.py
@@ -45,7 +45,7 @@ CacheDir(r'%s')
 g = '%s'
 
 def ActionWithUndeclaredInputs(target,source,env):
-    open(target[0].abspath,'w').write(g)
+    open(target[0].get_abspath(),'w').write(g)
 
 Command('foo_cached', [], ActionWithUndeclaredInputs)
 NoCache(Command('foo_notcached', [], ActionWithUndeclaredInputs))
diff --git a/test/Install/wrap-by-attribute.py b/test/Install/wrap-by-attribute.py
index 912551e..02513af 100644
--- a/test/Install/wrap-by-attribute.py
+++ b/test/Install/wrap-by-attribute.py
@@ -58,10 +58,10 @@ env.SconsInternalInstallFunc = env.Install
 env.SconsInternalInstallAsFunc = env.InstallAs
 
 def InstallWithDestDir(dir, source):
-    abspath = os.path.splitdrive(env.Dir(dir).abspath)[1]
+    abspath = os.path.splitdrive(env.Dir(dir).get_abspath())[1]
     return env.SconsInternalInstallFunc('$DESTDIR'+abspath, source)
 def InstallAsWithDestDir(target, source):
-    abspath = os.path.splitdrive(env.File(target).abspath)[1]
+    abspath = os.path.splitdrive(env.File(target).get_abspath())[1]
     return env.SconsInternalInstallAsFunc('$DESTDIR'+abspath, source)
 
 # Add the wrappers directly as attributes.
diff --git a/test/NoClean.py b/test/NoClean.py
index 01fe209..63e3e28 100644
--- a/test/NoClean.py
+++ b/test/NoClean.py
@@ -34,14 +34,14 @@ test = TestSCons.TestSCons()
 

 test.write('SConstruct', """

 def action(target, source, env):

-	for t in target: open(t.path, 'w')

+	for t in target: open(t.get_internal_path(), 'w')

 Command('1.out', 'SConstruct', action)

 NoClean('1.out')

 """)

 

 test.write('SConstruct.force', """

 def action(target, source, env):

-	for t in target: open(t.path, 'w')

+	for t in target: open(t.get_internal_path(), 'w')

 	open('4.out', 'w')

 res = Command('3.out', 'SConstruct.force', action)

 Clean('4.out', res)

@@ -50,7 +50,7 @@ NoClean('4.out')
 

 test.write('SConstruct.multi', """

 def action(target, source, env):

-	for t in target: open(t.path, 'w')

+	for t in target: open(t.get_internal_path(), 'w')

 Command(['5.out', '6.out'], 'SConstruct.multi', action)

 NoClean('6.out')

 """)

diff --git a/test/Scanner/exception.py b/test/Scanner/exception.py
index 5af7ac3..1a14152 100644
--- a/test/Scanner/exception.py
+++ b/test/Scanner/exception.py
@@ -79,7 +79,6 @@ env.Cat('foo', 'foo.k')
 
 bar_in = File('bar.in')
 env.Cat('bar', bar_in)
-bar_in.source_scanner = kscan
 """)
 
 test.write('foo.k', 
diff --git a/test/explain/function-actions.py b/test/explain/function-actions.py
index e5f9ba8..bd3ad01 100644
--- a/test/explain/function-actions.py
+++ b/test/explain/function-actions.py
@@ -59,8 +59,8 @@ if mode:
 else:
     MyCopy = Builder(action = Copy('$TARGET', '$SOURCE'))
     def ChangingCopy(target, source, env):
-        tgt = str(target[0].abspath)
-        src = str(source[0].abspath)
+        tgt = str(target[0].get_abspath())
+        src = str(source[0].get_abspath())
         shutil.copy(src, tgt)
     ChangingCopy = Builder(action = ChangingCopy)
 
diff --git a/test/implicit-cache/DualTargets.py b/test/implicit-cache/DualTargets.py
index f0694b1..45174ea 100644
--- a/test/implicit-cache/DualTargets.py
+++ b/test/implicit-cache/DualTargets.py
@@ -37,14 +37,14 @@ test.write('SConstruct', """\
 import os.path
 
 def emitter(target, source, env):
-    tgt0 = target[0].abspath
+    tgt0 = target[0].get_abspath()
     base,ext = os.path.splitext(tgt0)
     target.append(base + '.b')
     return(target, source)
 
 
 def source_scan(node, env, path):
-    path = node.abspath
+    path = node.get_abspath()
     base,ext = os.path.splitext(path)
     return [base + '.lib']
 
diff --git a/test/sconsign/script/SConsignFile.py b/test/sconsign/script/SConsignFile.py
index a9f79f4..74fb1f0 100644
--- a/test/sconsign/script/SConsignFile.py
+++ b/test/sconsign/script/SConsignFile.py
@@ -173,33 +173,33 @@ inc2.h: %(sig_re)s \d+ \d+
 
 test.run_sconsign(arguments = "--raw .sconsign",
          stdout = r"""=== .:
-SConstruct: {'csig': None, 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 1}
-fake_cc\.py: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 1}
-fake_link\.py: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 1}
+SConstruct: {'csig': None, 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 2}
+fake_cc\.py: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 2}
+fake_link\.py: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 2}
 === sub1:
-hello.c: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 1}
-hello.exe: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 1}
-        %(sub1_hello_obj)s: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 1}
-        fake_link\.py: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 1}
+hello.c: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 2}
+hello.exe: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 2}
+        %(sub1_hello_obj)s: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 2}
+        fake_link\.py: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 2}
         %(sig_re)s \[.*\]
-hello.obj: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 1}
-        %(sub1_hello_c)s: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 1}
-        fake_cc\.py: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 1}
+hello.obj: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 2}
+        %(sub1_hello_c)s: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 2}
+        fake_cc\.py: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 2}
         %(sig_re)s \[.*\]
 === sub2:
-hello.c: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 1}
-hello.exe: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 1}
-        %(sub2_hello_obj)s: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 1}
-        fake_link\.py: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 1}
+hello.c: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 2}
+hello.exe: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 2}
+        %(sub2_hello_obj)s: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 2}
+        fake_link\.py: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 2}
         %(sig_re)s \[.*\]
-hello.obj: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 1}
-        %(sub2_hello_c)s: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 1}
-        %(sub2_inc1_h)s: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 1}
-        %(sub2_inc2_h)s: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 1}
-        fake_cc\.py: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 1}
+hello.obj: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 2}
+        %(sub2_hello_c)s: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 2}
+        %(sub2_inc1_h)s: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 2}
+        %(sub2_inc2_h)s: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 2}
+        fake_cc\.py: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 2}
         %(sig_re)s \[.*\]
-inc1.h: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 1}
-inc2.h: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 1}
+inc1.h: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 2}
+inc2.h: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 2}
 """ % locals())
 
 expect = r"""=== .:
diff --git a/test/sconsign/script/no-SConsignFile.py b/test/sconsign/script/no-SConsignFile.py
index 829d650..09ecfa2 100644
--- a/test/sconsign/script/no-SConsignFile.py
+++ b/test/sconsign/script/no-SConsignFile.py
@@ -159,14 +159,14 @@ hello.obj: %(sig_re)s \d+ \d+
 test.run_sconsign(arguments = "sub1/.sconsign", stdout=expect)
 
 test.run_sconsign(arguments = "--raw sub1/.sconsign",
-         stdout = r"""hello.c: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 1}
-hello.exe: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 1}
-        %(sub1_hello_obj)s: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 1}
-        fake_link\.py: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 1}
+         stdout = r"""hello.c: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 2}
+hello.exe: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 2}
+        %(sub1_hello_obj)s: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 2}
+        fake_link\.py: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 2}
         %(sig_re)s \[.*\]
-hello.obj: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 1}
-        %(sub1_hello_c)s: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 1}
-        fake_cc\.py: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 1}
+hello.obj: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 2}
+        %(sub1_hello_c)s: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 2}
+        fake_cc\.py: {'csig': '%(sig_re)s', 'timestamp': \d+L?, 'size': \d+L?, '_version_id': 2}
         %(sig_re)s \[.*\]
 """ % locals())