Need instruction on how to use isinstance

[Chris Rebert]

On Sun, Jun 27, 2010 at 9:54 PM, Stephen Hansen
<me+list/python at ixokai.io> wrote:
> On 6/27/10 9:30 PM, alex23 wrote:
>> Stephen Hansen<me+list/pyt... at ixokai.io>  wrote:
>>> P.S. The removal of callable is something I don't understand in Python
>>> 3: while generally speaking I do really believe and use duck typing, I
>>> too have on occassion wanted to dispatch based on 'is callable? do x'.
>>> Sometimes its not convenient to do so via duck typing. Its rare. But it
>>> is there. That isinstance()/issubclass got a boost in power with the
>>> ABC's and registering, while at the same time the ability to introspect
>>> about the function-y callable-y ness of a function was removed? Makes no
>>> sense to me. But alas!
>>
>> There's always: isinstance(<object>, collections.Callable)
>
> What the hell? When did that show up? o.O (Did I not pay attention enough
> during the ABC conversations? It seemed so boring).
>
> A) how is Callable a collection, in any way shape or form?

Completely agree, see my prior reply.

> And B) does that
> really return True for everything callable-esque? (I don't have a 3.x to
> play with on this temporary computer)

You don't even need 3.x; it was added in 2.6. The new magic of
__instancecheck__ makes it possible.
See http://docs.python.org/reference/datamodel.html#customizing-instance-and-subclass-checks

Cheers,
Chris
--
Very cool new magic, eh?
http://blog.rebertia.com