Fix C optimizations broken on Py3k.

- The bare import of '_zope_c_optimizations' prevented them from being
  used.

- After enabling them via absolute imports, they would fail due to
  http://bugs.python.org/issue15657.

Fixes #60.

CHANGES.rst

@@ -4,7 +4,9 @@ Changes
 4.3.3 (unreleased)
 ------------------
 
-- Nothing changed yet.
+- Fix C optimizations broken on Py3k.  See the Python bug at:
+  http://bugs.python.org/issue15657
+  (https://github.com/zopefoundation/zope.interface/issues/60)
 
 
 4.3.2 (2016-09-05)

src/zope/interface/_zope_interface_coptimizations.c

@@ -25,6 +25,15 @@
 #define Py_TYPE(o) ((o)->ob_type)
 #endif
 
+#if PY_MAJOR_VERSION >= 3
+#define PY3K
+#endif
+
+#ifdef PY3K
+/* See http://bugs.python.org/issue15657 */
+#define METH_KEYWORDS 0x0003
+#endif
+
 static PyObject *str__dict__, *str__implemented__, *strextends;
 static PyObject *BuiltinImplementationSpecifications, *str__provides__;
 static PyObject *str__class__, *str__providedBy__;

src/zope/interface/adapter.py

@@ -398,7 +398,7 @@ def subscriptions(self, required, provided):
 LookupBasePy = LookupBaseFallback # BBB
 
 try:
-    from _zope_interface_coptimizations import LookupBase
+    from zope.interface._zope_interface_coptimizations import LookupBase
 except ImportError: #pragma NO COVER
     LookupBase = LookupBaseFallback
 
@@ -434,7 +434,7 @@ def subscriptions(self, required, provided):
 VerifyingBasePy = VerifyingBaseFallback #BBB
 
 try:
-    from _zope_interface_coptimizations import VerifyingBase
+    from zope.interface._zope_interface_coptimizations import VerifyingBase
 except ImportError: #pragma NO COVER
     VerifyingBase = VerifyingBaseFallback
 

src/zope/interface/declarations.py

@@ -640,11 +640,11 @@ def __get__(self, inst, cls):
 
 # Try to get C base:
 try:
-    import _zope_interface_coptimizations
+    import zope.interface._zope_interface_coptimizations
 except ImportError:  #pragma NO COVERAGE
     pass
 else:  #pragma NO COVERAGE
-    from _zope_interface_coptimizations import ClassProvidesBase
+    from zope.interface._zope_interface_coptimizations import ClassProvidesBase
 
 
 class ClassProvides(Declaration, ClassProvidesBase):
@@ -917,13 +917,15 @@ def _normalizeargs(sequence, output = None):
 _empty = Declaration()
 
 try:
-    import _zope_interface_coptimizations
+    import zope.interface._zope_interface_coptimizations
 except ImportError: #pragma NO COVER
     pass
 else: #pragma NO COVER PyPy
-    from _zope_interface_coptimizations import implementedBy
-    from _zope_interface_coptimizations import providedBy
-    from _zope_interface_coptimizations import getObjectSpecification
-    from _zope_interface_coptimizations import ObjectSpecificationDescriptor
+    from zope.interface._zope_interface_coptimizations import implementedBy
+    from zope.interface._zope_interface_coptimizations import providedBy
+    from zope.interface._zope_interface_coptimizations import (
+        getObjectSpecification)
+    from zope.interface._zope_interface_coptimizations import (
+        ObjectSpecificationDescriptor)
 
 objectSpecificationDescriptor = ObjectSpecificationDescriptor()

src/zope/interface/interface.py

@@ -114,7 +114,7 @@ def isOrExtends(self, interface):
 
 SpecificationBase = SpecificationBasePy
 try:
-    from _zope_interface_coptimizations import SpecificationBase
+    from zope.interface._zope_interface_coptimizations import SpecificationBase
 except ImportError: #pragma NO COVER
     pass
 
@@ -155,14 +155,14 @@ def __adapt__(self, obj):
 
 InterfaceBase = InterfaceBasePy
 try:
-    from _zope_interface_coptimizations import InterfaceBase
+    from zope.interface._zope_interface_coptimizations import InterfaceBase
 except ImportError: #pragma NO COVER
     pass
 
 
 adapter_hooks = []
 try:
-    from _zope_interface_coptimizations import adapter_hooks
+    from zope.interface._zope_interface_coptimizations import adapter_hooks
 except ImportError: #pragma NO COVER
     pass