isinstance() and multiple inheritance/ctypes

Steven D'Aprano steve at
Thu Aug 27 14:59:11 CEST 2015

On Thu, 27 Aug 2015 09:14 am, Chris Angelico wrote:

> On Thu, Aug 27, 2015 at 9:12 AM, Chris Angelico <rosuav at> wrote:
>> Or is there a magic __isinstance__
> Argh, keyed the wrong thing and sent the post prematurely. Meant to say:
> Or is there a magic __instancecheck__ method somewhere that I'm not aware
> of?

Yes -- see Terry Reedy's post. 

isinstance(inst, klass) ends up calling 

type(klass).__instancecheck__(klass, inst)


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