fix decorator lookup by avoiding (re-)assignments to the function/class name...

fix decorator lookup by avoiding (re-)assignments to the function/class name before their execution (ticket #593)

Cython/Compiler/Nodes.py

@@ -2326,6 +2326,13 @@ class DefNode(FuncDefNode):
             else:
                 rhs.binding = False
 
+        if self.decorators:
+            for decorator in self.decorators[::-1]:
+                rhs = ExprNodes.SimpleCallNode(
+                    decorator.pos,
+                    function = decorator.decorator,
+                    args = [rhs])
+
         self.assmt = SingleAssignmentNode(self.pos,
             lhs = ExprNodes.NameNode(self.pos, name = self.name),
             rhs = rhs)
@@ -3198,8 +3205,9 @@ class PyClassDefNode(ClassDefNode):
     #  classobj ClassNode  Class object
     #  target   NameNode   Variable to assign class object to
 
-    child_attrs = ["body", "dict", "metaclass", "mkw", "bases", "classobj", "target"]
+    child_attrs = ["body", "dict", "metaclass", "mkw", "bases", "class_result", "target"]
     decorators = None
+    class_result = None
     py3_style_class = False # Python3 style class (bases+kwargs)
 
     def __init__(self, pos, name, bases, doc, body, decorators = None,
@@ -3302,6 +3310,16 @@ class PyClassDefNode(ClassDefNode):
         return cenv
 
     def analyse_declarations(self, env):
+        class_result = self.classobj
+        if self.decorators:
+            from ExprNodes import SimpleCallNode
+            for decorator in self.decorators[::-1]:
+                class_result = SimpleCallNode(
+                    decorator.pos,
+                    function = decorator.decorator,
+                    args = [class_result])
+        self.class_result = class_result
+        self.class_result.analyse_declarations(env)
         self.target.analyse_target_declaration(env)
         cenv = self.create_scope(env)
         cenv.directives = env.directives
@@ -3314,7 +3332,7 @@ class PyClassDefNode(ClassDefNode):
             self.metaclass.analyse_expressions(env)
             self.mkw.analyse_expressions(env)
         self.dict.analyse_expressions(env)
-        self.classobj.analyse_expressions(env)
+        self.class_result.analyse_expressions(env)
         genv = env.global_scope()
         cenv = self.scope
         self.body.analyse_expressions(cenv)
@@ -3334,9 +3352,9 @@ class PyClassDefNode(ClassDefNode):
         self.dict.generate_evaluation_code(code)
         cenv.namespace_cname = cenv.class_obj_cname = self.dict.result()
         self.body.generate_execution_code(code)
-        self.classobj.generate_evaluation_code(code)
+        self.class_result.generate_evaluation_code(code)
         cenv.namespace_cname = cenv.class_obj_cname = self.classobj.result()
-        self.target.generate_assignment_code(self.classobj, code)
+        self.target.generate_assignment_code(self.class_result, code)
         self.dict.generate_disposal_code(code)
         self.dict.free_temps(code)
         if self.py3_style_class:
@@ -3424,6 +3442,9 @@ class CClassDefNode(ClassDefNode):
         if env.in_cinclude and not self.objstruct_name:
             error(self.pos, "Object struct name specification required for "
                 "C class defined in 'extern from' block")
+        if self.decorators:
+            error(self.pos,
+                  "Decorators not allowed on cdef classes (used on type '%s')" % self.class_name)
         self.base_type = None
         # Now that module imports are cached, we need to
         # import the modules for extern classes.

Cython/Compiler/ParseTreeTransforms.py

@@ -1193,39 +1193,23 @@ class WithTransform(CythonTransform, SkipDeclarations):
         return node
 
 
-class DecoratorTransform(CythonTransform, SkipDeclarations):
+class DecoratorTransform(ScopeTrackingTransform, SkipDeclarations):
+    """Originally, this was the only place where decorators were
+    transformed into the corresponding calling code.  Now, this is
+    done directly in DefNode and PyClassDefNode to avoid reassignments
+    to the function/class name - except for cdef class methods.  For
+    those, the reassignment is required as methods are originally
+    defined in the PyMethodDef struct.
+    """
 
     def visit_DefNode(self, func_node):
-        self.visitchildren(func_node)
-        if not func_node.decorators:
+        scope_type = self.scope_type
+        func_node = self.visit_FuncDefNode(func_node)
+        if scope_type is not 'cclass' or not func_node.decorators:
             return func_node
         return self._handle_decorators(
             func_node, func_node.name)
 
-    def visit_CClassDefNode(self, class_node):
-        # This doesn't currently work, so it's disabled.
-        #
-        # Problem: assignments to cdef class names do not work.  They
-        # would require an additional check anyway, as the extension
-        # type must not change its C type, so decorators cannot
-        # replace an extension type, just alter it and return it.
-
-        self.visitchildren(class_node)
-        if not class_node.decorators:
-            return class_node
-        error(class_node.pos,
-              "Decorators not allowed on cdef classes (used on type '%s')" % class_node.class_name)
-        return class_node
-        #return self._handle_decorators(
-        #    class_node, class_node.class_name)
-
-    def visit_ClassDefNode(self, class_node):
-        self.visitchildren(class_node)
-        if not class_node.decorators:
-            return class_node
-        return self._handle_decorators(
-            class_node, class_node.name)
-
     def _handle_decorators(self, node, name):
         decorator_result = ExprNodes.NameNode(node.pos, name = name)
         for decorator in node.decorators[::-1]:

Cython/Compiler/Tests/TestDecorators.py

-import unittest
-from Cython.TestUtils import TransformTest
-from Cython.Compiler.ParseTreeTransforms import DecoratorTransform
-
-class TestDecorator(TransformTest):
-
-    def test_decorator(self):
-        t = self.run_pipeline([DecoratorTransform(None)], u"""
-        def decorator(fun):
-            return fun
-        @decorator
-        def decorated():
-            pass
-        """)
-
-        self.assertCode(u"""
-        def decorator(fun):
-            return fun
-        def decorated():
-            pass
-        decorated = decorator(decorated)
-        """, t)
-
-if __name__ == '__main__':
-    unittest.main()