On Thu, Jan 27, 2011 at 20:05, Alan Franzoni <mail...@franzoni.eu> wrote: > On Thu, Jan 27, 2011 at 8:03 PM, Alan Franzoni <mail...@franzoni.eu> wrote: >> 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. > > On the contrary, now that I double checked, it can't be used that way; > I don't want to modify the object I'm testing (it could be a third > party object) nor I want to force it to be "registered" as a certain > ABC; so __instancecheck__() is just useless here.
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. Daniel -- http://mail.python.org/mailman/listinfo/python-list
