Hey all, Using bases in a metaclass, I've been able to easily figure out when an attribute is being added to an instance of a class. However, what I'm /actually/ looking to do is to intercept when attributes are being added to a class (not an instance of). I thought that I'd be able to do so by passing in a subclass of dict to type.__new__ of the metaclass's __new__ and implementing a custom __setitem__, but apparently that's not the case.
If you're curious as to why I'm doing this, I'm trying to clean up https://gist.github.com/demianbrecht/6944269 and get rid of the late_bind method there in favour of using the appropriate magic methods. The intention is to piggyback off of abc's __abstractmethods__ in order to implement a "looks_like" method that checks that one class conforms to an unrelated class's interface rather than using inheritance to enforce interface implementations at class creation time. This is /only/ intended to be a proof of concept for demonstration purposes and nothing that I'd ever actually implement, so no need for flaming the concept :) # test.py class Dict(dict): def __setattr__(self, key, value): print 'Dict.__setattr__' dict.__setattr__(self, key, value) def __setitem__(self, key, value): print 'Dict.__setitem__' dict.__setitem__(self, key, value) class Bar(object): def __setattr__(self, key, value): print 'Bar.__setattr__' object.__setattr__(self, key, value) class metafoo(type): def __new__(mcls, name, bases, dct): return type.__new__(mcls, name, (Bar,), Dict(dct)) class Foo(object): __metaclass__ = metafoo >>> import test >>> f = test.Foo() >>> f.foo = 'bar' Bar.__setattr__ # expected >>> test.Foo.foo = 'bar' # I'm expecting Dict.__setattr__ here, but... *crickets* Am I missing something here, or do I just have to live with what I currently have in my gist? Thanks, -- Demian Brecht http://demianbrecht.github.com -- https://mail.python.org/mailman/listinfo/python-list
