SF patch #1438387, PEP 328: relative and absolute imports.

 - IMPORT_NAME takes an extra argument from the stack: the relativeness of
   the import. Only passed to __import__ when it's not -1.

 - __import__() takes an optional 5th argument for the same thing; it
   __defaults to -1 (old semantics: try relative, then absolute)

 - 'from . import name' imports name (be it module or regular attribute)
   from the current module's *package*. Likewise, 'from .module import name'
   will import name from a sibling to the current module.

 - Importing from outside a package is not allowed; 'from . import sys' in a
   toplevel module will not work, nor will 'from .. import sys' in a
   (single-level) package.

 - 'from __future__ import absolute_import' will turn on the new semantics
   for import and from-import: imports will be absolute, except for
   from-import with dots.

Includes tests for regular imports and importhooks, parser changes and a
NEWS item, but no compiler-package changes or documentation changes.

3 files changed, 47 insertions, 1 deletions

diff --git a/Lib/__future__.py b/Lib/__future__.py
index fc47459..e49c663 100644
--- a/Lib/__future__.py
+++ b/Lib/__future__.py
@@ -51,6 +51,7 @@ all_feature_names = [
     "nested_scopes",
     "generators",
     "division",
+    "absolute_import",
 ]
 
 __all__ = ["all_feature_names"] + all_feature_names
@@ -62,6 +63,7 @@ __all__ = ["all_feature_names"] + all_feature_names
 CO_NESTED            = 0x0010   # nested_scopes
 CO_GENERATOR_ALLOWED = 0        # generators (obsolete, was 0x1000)
 CO_FUTURE_DIVISION   = 0x2000   # division
+CO_FUTURE_ABSIMPORT  = 0x4000   # absolute_import
 
 class _Feature:
     def __init__(self, optionalRelease, mandatoryRelease, compiler_flag):
@@ -102,3 +104,7 @@ generators = _Feature((2, 2, 0, "alpha", 1),
 division = _Feature((2, 2, 0, "alpha", 2),
                     (3, 0, 0, "alpha", 0),
                     CO_FUTURE_DIVISION)
+
+absolute_import = _Feature((2, 5, 0, "alpha", 1),
+                           (2, 7, 0, "alpha", 0),
+                           CO_FUTURE_ABSIMPORT)
diff --git a/Lib/test/test_ast.py b/Lib/test/test_ast.py
index 331e96e..83a1baa 100644
--- a/Lib/test/test_ast.py
+++ b/Lib/test/test_ast.py
@@ -145,7 +145,7 @@ exec_results = [
 ('Module', [('TryFinally', [('Pass',)], [('Pass',)])]),
 ('Module', [('Assert', ('Name', 'v', ('Load',)), None)]),
 ('Module', [('Import', [('alias', 'sys', None)])]),
-('Module', [('ImportFrom', 'sys', [('alias', 'v', None)])]),
+('Module', [('ImportFrom', 'sys', [('alias', 'v', None)], 0)]),
 ('Module', [('Exec', ('Str', 'v'), None, None)]),
 ('Module', [('Global', ['v'])]),
 ('Module', [('Expr', ('Num', 1))]),
diff --git a/Lib/test/test_importhooks.py b/Lib/test/test_importhooks.py
index 9304213..c580755 100644
--- a/Lib/test/test_importhooks.py
+++ b/Lib/test/test_importhooks.py
@@ -12,6 +12,10 @@ def get_file():
     return __file__
 """
 
+absimp = "import sub\n"
+relimp = "from . import sub\n"
+futimp = "from __future__ import absolute_import\n"
+
 reload_src = test_src+"""\
 reloaded = True
 """
@@ -19,6 +23,11 @@ reloaded = True
 test_co = compile(test_src, "<???>", "exec")
 reload_co = compile(reload_src, "<???>", "exec")
 
+test2_oldabs_co = compile(absimp + test_src, "<???>", "exec")
+test2_newabs_co = compile(futimp + absimp + test_src, "<???>", "exec")
+test2_newrel_co = compile(relimp + test_src, "<???>", "exec")
+test2_futrel_co = compile(futimp + relimp + test_src, "<???>", "exec")
+
 test_path = "!!!_test_!!!"
 
 
@@ -38,6 +47,11 @@ class TestImporter:
         "hooktestpackage": (True, test_co),
         "hooktestpackage.sub": (True, test_co),
         "hooktestpackage.sub.subber": (False, test_co),
+        "hooktestpackage.oldabs": (False, test2_oldabs_co),
+        "hooktestpackage.newabs": (False, test2_newabs_co),
+        "hooktestpackage.newrel": (False, test2_newrel_co),
+        "hooktestpackage.futrel": (False, test2_futrel_co),
+        "sub": (False, test_co),
         "reloadmodule": (False, test_co),
     }
 
@@ -176,6 +190,32 @@ class ImportHooksTestCase(ImportHooksBaseTestCase):
         TestImporter.modules['reloadmodule'] = (False, reload_co)
         reload(reloadmodule)
         self.failUnless(hasattr(reloadmodule,'reloaded'))
+        
+        import hooktestpackage.oldabs
+        self.assertEqual(hooktestpackage.oldabs.get_name(),
+                         "hooktestpackage.oldabs")
+        self.assertEqual(hooktestpackage.oldabs.sub,
+                         hooktestpackage.sub)
+
+        import hooktestpackage.newrel
+        self.assertEqual(hooktestpackage.newrel.get_name(),
+                         "hooktestpackage.newrel")
+        self.assertEqual(hooktestpackage.newrel.sub,
+                         hooktestpackage.sub)
+
+        import hooktestpackage.futrel
+        self.assertEqual(hooktestpackage.futrel.get_name(),
+                         "hooktestpackage.futrel")
+        self.assertEqual(hooktestpackage.futrel.sub,
+                         hooktestpackage.sub)
+        
+        import sub
+        self.assertEqual(sub.get_name(), "sub")
+
+        import hooktestpackage.newabs
+        self.assertEqual(hooktestpackage.newabs.get_name(),
+                         "hooktestpackage.newabs")
+        self.assertEqual(hooktestpackage.newabs.sub, sub)
 
     def testMetaPath(self):
         i = MetaImporter()