Patch bundled simplegeneric for Python 3 compatibility.

IPython/external/simplegeneric/_simplegeneric.py

@@ -1,99 +1,109 b''
 """This is version 0.7 of Philip J. Eby's simplegeneric module
-(http://pypi.python.org/pypi/simplegeneric)
+(http://pypi.python.org/pypi/simplegeneric), patched to work with Python 3,
+which doesn't support old-style classes.
 """
 
 #Name: simplegeneric
 #Version: 0.7
 #Summary: Simple generic functions (similar to Python's own len(), pickle.dump(), etc.)
 #Home-page: http://pypi.python.org/pypi/simplegeneric
 #Author: Phillip J. Eby
 #Author-email: [e-mail]
 #License: PSF or ZPL
 
 __all__ = ["generic"]
 
+try:
 from types import ClassType, InstanceType
+except ImportError:
+    classtypes = type
+else:
 classtypes = type, ClassType
 
 def generic(func):
     """Create a simple generic function"""
 
     _sentinel = object()
 
     def _by_class(*args, **kw):
         cls = args[0].__class__
         for t in type(cls.__name__, (cls,object), {}).__mro__:
             f = _gbt(t, _sentinel)
             if f is not _sentinel:
                 return f(*args, **kw)
         else:
             return func(*args, **kw)
 
-    _by_type = {object: func, InstanceType: _by_class}
+    _by_type = {object: func}
+    try:
+        _by_type[InstanceType] = _by_class
+    except NameError:   # Python 3
+        pass
+    
     _gbt = _by_type.get
 
     def when_type(*types):
         """Decorator to add a method that will be called for the given types"""
         for t in types:
             if not isinstance(t, classtypes):
                 raise TypeError(
                     "%r is not a type or class" % (t,)
                 )
         def decorate(f):
             for t in types:
                 if _by_type.setdefault(t,f) is not f:
                     raise TypeError(
                         "%r already has method for type %r" % (func, t)
                     )
             return f
         return decorate
 
 
 
 
     _by_object = {}
     _gbo = _by_object.get
 
     def when_object(*obs):
         """Decorator to add a method to be called for the given object(s)"""
         def decorate(f):
             for o in obs:
                 if _by_object.setdefault(id(o), (o,f))[1] is not f:
                     raise TypeError(
                         "%r already has method for object %r" % (func, o)
                     )
             return f
         return decorate
 
 
     def dispatch(*args, **kw):
         f = _gbo(id(args[0]), _sentinel)
         if f is _sentinel:
             for t in type(args[0]).__mro__:
                 f = _gbt(t, _sentinel)
                 if f is not _sentinel:
                     return f(*args, **kw)
             else:
                 return func(*args, **kw)
         else:
             return f[1](*args, **kw)
 
     dispatch.__name__       = func.__name__
     dispatch.__dict__       = func.__dict__.copy()
     dispatch.__doc__        = func.__doc__
     dispatch.__module__     = func.__module__
 
     dispatch.when_type = when_type
     dispatch.when_object = when_object
     dispatch.default = func
     dispatch.has_object = lambda o: id(o) in _by_object
     dispatch.has_type   = lambda t: t in _by_type
     return dispatch
 
 
 def test_suite():
     import doctest
     return doctest.DocFileSuite(
         'README.txt',
         optionflags=doctest.ELLIPSIS|doctest.REPORT_ONLY_FIRST_FAILURE,
     )