On Fri, Jan 28, 2011 at 11:32, Alan Franzoni <mail...@franzoni.eu> wrote: > On Thu, Jan 27, 2011 at 11:41 PM, Daniel Urban <urban.d...@gmail.com> wrote: > >> Actually it can. You don't have to modify the object, just check for >> the desired methods/signature/whatever. See for example the >> implementation of collections.Hashable.__subclasshook__ in _abcoll.py >> and the abc.ABCMeta.__instancecheck__ method. > > Mmh, I don't get your examples (subclasshook checks for *classes*, not > instances, and ABCMeta is a metaclass whose instance is an ABC), but > after properly looking at the PEP (__instancecheck__ seems to be > poorly documented in python standard docs) I've seen that yes, > __instancecheck__ on an ABC can actually be used in place of > maybe_implemented_by and hooking into isinstance().
Exactly. I mentioned subclasshook because it is possible to define a similar "instancehook", which would check for instances. Daniel -- http://mail.python.org/mailman/listinfo/python-list
