TypeError: Cannot create a consistent method resolution order (MRO) for bases object

[digitalorganics at gmail.com]

Hint: If I change Dog and Bat to old-style classes, there's no problem,
everything works fine.


Okay, here's the code dump from my playground::
------------------------------------------
#!/usr/bin/env python

class Mixin:
    def mixin(object, *classes):
        NewClass = type('Mixin', (object.__class__,) + classes, {})
        newobj = NewClass()
        newobj.__dict__.update(object.__dict__)
        return newobj

class Cat(object):
    def __init__(self):
        self.love = 0
    def meow(self):
        print "meow"
class Dog(object):
    def bark(self):
        print "bark"
class Bat(object):
    def scream(self):
        print "scream"

mycat = Cat()
mycat.love = 4
mycat.__class__.__bases__ += (Mixin,)
mycat.mixin(Dog, Bat)
print mycat.love

def isClass(object):
    if isinstance(object, type):
        return True
    elif isinstance(object, types.ClassType):
        return True
    else:
        return False

def listClasses():
    classes = []
    for eachobj in globals().keys():
        if isClass(globals()[eachobj]):
            classes.append(globals()[eachobj])
            print eachobj
    return classes

def applyMixinGlobal(*Mixins):
    for eachclass in listClasses():
        MixInto(eachclass, Mixins)
#applyMixinGlobal(Mixin)

def MixInto(Class, *Mixins):
    for eachMixin in Mixins:
        if eachMixin not in Class.__bases__:
            Class.__bases__ += (eachMixin,)
MixInto(Bat, Mixin)
Bat.__bases__ += (Dog,)
dargo = Bat()
dargo = dargo.mixin(Cat)
dargo.meow()

Simon Forman wrote:
> digitalorganics at gmail.com wrote:
> > What are the reason one would get this error: TypeError: Cannot create
> > a consistent method resolution order (MRO) for bases object ??
> >
> > I can provide the code if needed....
> 
> Yes, do that.
> 
> That's an amazing error.
> 
> ~Simon