Behaviour-based interface/protocol implementation?

[Alan Franzoni]

On Wed, Jan 26, 2011 at 7:23 PM, Daniel Urban <urban.dani at gmail.com> wrote:
>> That's just what I'd like and I suppose can't be currently done with
>> current ABC, PyProtocols or zope.interface implementations, right?
>
> It can. With __instancecheck__ you can override isinstance. It is
> possible (for example) to write a subclass of abc.ABCMeta, which
> extends __instancecheck__ to use an _instancehook classmethod
> similarly to __subclasshook__. Then in your MyInterface class you can
> implement _instancehook to check for methods/signatures/whatever you
> want.

Yes, __instancecheck__ could be used as an alternative hook with
respect to maybe_implemented_by(), but there's no such logic for
signature checking. That's a minor detail, I think.


-- 
Alan Franzoni
--
contact me at public@[mysurname].eu