On Sat, 29 Oct 2011 14:06:12 -0700, Geoff Bache wrote: > Hi, > > I'm wondering if there is any way to customize class attribute access on > classic classes? > > So this works: > > class Meta(type): > def __getattr__(cls, name): > return "Customized " + name > > class A: > __metaclass__ = Meta > > print A.blah > > but it turns A into a new-style class.
And why is this a problem? In any case, metaclasses work for classic classes. Metaclasses go back to pre-Python 1.5, long before new-style classes and type unification. http://www.python.org/doc/essays/metaclasses/ You just have to do a lot more work: class Meta: def __init__(self, name, bases, namespace): self.__name__ = name self.__bases__ = bases self.__dict__ = namespace def __str__(self): return "<Meta instance>" __repr__ = __str__ def __getattr__(self, name): return "Customized " + name def __call__(self): return self (The purpose of the __str__ and __repr__ methods is to make it possible to experiment in the interactive interpreter, without a lot of mysterious and puzzling "str object is not callable" TypeErrors. Trust me on this.) And in use: >>> class Spam: ... __metaclass__ = Meta ... a = 1 ... >>> Spam.b 'Customized b' But note that using classic classes, there is no equivalent of __getattribute__ or descriptors, so there is no way to customize access of an attribute which actually does exist: >>> Spam.a 1 -- Steven -- http://mail.python.org/mailman/listinfo/python-list
