On Wed, 28 Jul 2010 22:45:19 -0700, John Nagle wrote: [...] >> if you have an instance of class A, you can do this: >> >> a = A() # make an instance of class A >> a.__class__ = B # tell it that it's now class B >> >> and hope that it won't explode when you try to use it :/ [...] > The main use for that sort of thing is in constructing objects > without their cooperation. "copy" and "pickle" do that, as they build > up objects without running their initializers.
True, but there are other use-cases as well, such as the recipe for ring buffer which made it into the Python Cookbook. I think this is it: http://code.activestate.com/recipes/68429-ring-buffer/ > Storing into "__class__" > may not be portable across Python implementations. The implications for > multiple inheritance are difficult. It's really a hack for CPython. I believe that it is intended as a language feature, not an implementation-specific hack: http://bytes.com/topic/python/answers/449635-assigning-self-__class__ While it's an advanced technique that isn't terribly common, I don't see any reason to avoid it. -- Steven -- http://mail.python.org/mailman/listinfo/python-list
