Explicitly check if an object is a class is pydispatch.

* This is to fix a disagreement in between CPython and PyPy.
* https://gist.github.com/4220533

scrapy/xlib/pydispatch/robustapply.py

@@ -6,6 +6,8 @@
 those which are acceptable.
 """
 
+import inspect
+
 def function( receiver ):
 	"""Get function-like callable object for given receiver
 
@@ -14,7 +16,7 @@ def function( receiver ):
 	If fromMethod is true, then the callable already
 	has its first argument bound
 	"""
-	if hasattr(receiver, '__call__'):
+	if inspect.isclass(receiver) and hasattr(receiver, '__call__'):
 		# receiver is a class instance; assume it is callable.
 		# Reassign receiver to the actual method that will be called.
 		if hasattr( receiver.__call__, 'im_func') or hasattr( receiver.__call__, 'im_code'):
@@ -46,4 +48,4 @@ def robustApply(receiver, *arguments, **named):
 				del named[arg]
 	return receiver(*arguments, **named)
 
-
+