Use C3 (mostly) to compute IRO.issue21

Fixes #21

The 'mostly' is because interfaces are used in cases that C3 forbids;
when there's a conflict, we fallback to the legacy algorithm. It turns
out there are few conflicts (13K out of 149K total orderings in Plone).

I hoped the fix for #8 might shake out automatically, but it didn't.

Optimize the extremely common case of a __bases__ of length one.

In the benchmark, 4/5 of the interfaces and related objects have a base of length one.

Fix the bad IROs in the bundled ABC interfaces, and implement a way to get warnings or errors.

In running plone/buildout.coredev and tracking the RO requests, the
stats for equal, not equal, and inconsistent-so-fallback, I got
{'ros': 148868, 'eq': 138461, 'ne': 10407, 'inconsistent': 12934}

Add the interface module to the Attribute str.

This was extremely helpful tracking down the Plone problem; IDate is defined in multiple modules.

1 files changed, 10 insertions, 6 deletions

diff --git a/src/zope/interface/common/__init__.py b/src/zope/interface/common/__init__.py
index acbc581..a8bedf0 100644
--- a/src/zope/interface/common/__init__.py
+++ b/src/zope/interface/common/__init__.py
@@ -121,19 +121,20 @@ class ABCInterfaceClass(InterfaceClass):
         # go ahead and give us a name to ease debugging.
         self.__name__ = name
         extra_classes = attrs.pop('extra_classes', ())
+        ignored_classes = attrs.pop('ignored_classes', ())
 
         if 'abc' not in attrs:
             # Something like ``IList(ISequence)``: We're extending
             # abc interfaces but not an ABC interface ourself.
-            self.__class__ = InterfaceClass
             InterfaceClass.__init__(self, name, bases, attrs)
-            for cls in extra_classes:
-                classImplements(cls, self)
+            ABCInterfaceClass.__register_classes(self, extra_classes, ignored_classes)
+            self.__class__ = InterfaceClass
             return
 
         based_on = attrs.pop('abc')
         self.__abc = based_on
         self.__extra_classes = tuple(extra_classes)
+        self.__ignored_classes = tuple(ignored_classes)
 
         assert name[1:] == based_on.__name__, (name, based_on)
         methods = {
@@ -216,11 +217,14 @@ class ABCInterfaceClass(InterfaceClass):
         method.positional = method.positional[1:]
         return method
 
-    def __register_classes(self):
+    def __register_classes(self, conformers=None, ignored_classes=None):
         # Make the concrete classes already present in our ABC's registry
         # declare that they implement this interface.
-
-        for cls in self.getRegisteredConformers():
+        conformers = conformers if conformers is not None else self.getRegisteredConformers()
+        ignored = ignored_classes if ignored_classes is not None else self.__ignored_classes
+        for cls in conformers:
+            if cls in ignored:
+                continue
             classImplements(cls, self)
 
     def getABC(self):