kj <no.em...@please.post> wrote: > Watch this: > >>>> class neodict(dict): pass > ... >>>> d = neodict() >>>> type(d) ><class '__main__.neodict'> >>>> type(d.copy()) ><type 'dict'> > > > Bug? Feature? Genius beyond the grasp of schlubs like me?
Feature. In (almost?) all cases any objects constructed by a subclass of a builtin class will be of the original builtin class. So, for example, subclass a string and concatenating your subclassed objects still produces a string. This is reasonable behaviour as for builtin classes performance is more important than fully implementing polymorphism. If you want to subclass a builtin class you need to be aware of this and override the behaviour where it matters. Why do you want to subclass a dict anyway? It is usually the wrong choice. -- Duncan Booth http://kupuguy.blogspot.com -- http://mail.python.org/mailman/listinfo/python-list
