Allow Alias Nodes to have Actions.

4 files changed, 55 insertions, 24 deletions

diff --git a/src/engine/SCons/Node/Alias.py b/src/engine/SCons/Node/Alias.py
index 89127a3..c361838 100644
--- a/src/engine/SCons/Node/Alias.py
+++ b/src/engine/SCons/Node/Alias.py
@@ -39,11 +39,15 @@ import SCons.Node
 import SCons.Util
 
 class AliasNameSpace(UserDict.UserDict):
-    def Alias(self, name):
-        if self.has_key(name):
-            raise SCons.Errors.UserError
-        self[name] = SCons.Node.Alias.Alias(name)
-        return self[name]
+    def Alias(self, name, **kw):
+        if isinstance(name, SCons.Node.Alias.Alias):
+            return name
+        try:
+            a = self[name]
+        except KeyError:
+            a = apply(SCons.Node.Alias.Alias, (name,), kw)
+            self[name] = a
+        return a
 
     def lookup(self, name):
         try:
@@ -59,18 +63,11 @@ class Alias(SCons.Node.Node):
     def __str__(self):
         return self.name
 
-    def build(self):
-        """A "builder" for aliases."""
-        pass
-
+    really_build = SCons.Node.Node.build
     current = SCons.Node.Node.children_are_up_to_date
 
-    def sconsign(self):
-        """An Alias is not recorded in .sconsign files"""
-        pass
-
     def is_under(self, dir):
-        # Make Alias nodes get built regardless of 
+        # Make Alias nodes get built regardless of
         # what directory scons was run from. Alias nodes
         # are outside the filesystem:
         return 1
@@ -82,7 +79,25 @@ class Alias(SCons.Node.Node):
         for kid in self.children(None):
             contents = contents + kid.get_contents()
         return contents
-        
+
+    def sconsign(self):
+        """An Alias is not recorded in .sconsign files"""
+        pass
+
+    #
+    #
+    #
+
+    def build(self):
+        """A "builder" for aliases."""
+        pass
+
+    def convert(self):
+        try: del self.builder
+        except AttributeError: pass
+        self.reset_executor()
+        self.build = self.really_build
+
 default_ans = AliasNameSpace()
 
 SCons.Node.arg2nodes_lookups.append(default_ans.lookup)
diff --git a/src/engine/SCons/Node/AliasTests.py b/src/engine/SCons/Node/AliasTests.py
index afae46b..417cc2b 100644
--- a/src/engine/SCons/Node/AliasTests.py
+++ b/src/engine/SCons/Node/AliasTests.py
@@ -42,15 +42,11 @@ class AliasTestCase(unittest.TestCase):
         """
         ans = SCons.Node.Alias.AliasNameSpace()
 
-        a = ans.Alias('a1')
-	assert a.name == 'a1', a.name
-
-        try:
-            ans.Alias('a1')
-        except SCons.Errors.UserError:
-            pass
-        else:
-            raise TestFailed, "did not catch expected UserError"
+        a1 = ans.Alias('a1')
+        assert a1.name == 'a1', a1.name
+
+        a2 = ans.Alias('a1')
+        assert a1 is a2, (a1, a2)
 
     def test_lookup(self):
         """Test the lookup() method
diff --git a/src/engine/SCons/Node/NodeTests.py b/src/engine/SCons/Node/NodeTests.py
index 657ac9b..e0956e1 100644
--- a/src/engine/SCons/Node/NodeTests.py
+++ b/src/engine/SCons/Node/NodeTests.py
@@ -390,6 +390,19 @@ class NodeTestCase(unittest.TestCase):
         n1.builder_set(Builder(is_explicit=None))
         assert not n1.has_explicit_builder()
 
+    def test_get_builder(self):
+        """Test the get_builder() method"""
+        n1 = SCons.Node.Node()
+        b = n1.get_builder()
+        assert b is None, b
+        b = n1.get_builder(777)
+        assert b == 777, b
+        n1.builder_set(888)
+        b = n1.get_builder()
+        assert b == 888, b
+        b = n1.get_builder(999)
+        assert b == 888, b
+
     def test_multiple_side_effect_has_builder(self):
         """Test the multiple_side_effect_has_builder() method
         """
diff --git a/src/engine/SCons/Node/__init__.py b/src/engine/SCons/Node/__init__.py
index 36b0aed..fc3d7ec 100644
--- a/src/engine/SCons/Node/__init__.py
+++ b/src/engine/SCons/Node/__init__.py
@@ -329,6 +329,13 @@ class Node:
         directories)."""
         return self.has_builder() and self.builder.is_explicit
 
+    def get_builder(self, default_builder=None):
+        """Return the set builder, or a specified default value"""
+        try:
+            return self.builder
+        except AttributeError:
+            return default_builder
+
     multiple_side_effect_has_builder = has_builder
 
     def is_derived(self):