[Python-Dev] Why are so many built-in types inheritable? (original) (raw)

Fabiano Sidler fabianosidler at gmail.com
Mon Mar 13 21:29:06 CET 2006


Hi folks!

Let me explain the above question: For debugging purpose I tried this:

--- snip --- def foo(): pass function = type(foo)

class PrintingFunction(function): def init(self, func): self.func = func def call(self, *args, **kwargs): print args, kwargs return function.call(self, args, kwargs)

class DebugMeta(type): def new(self, name, bases, dict): for name in dict: if type(dict[name]) is function: dict[name] = PrintingFunction(dict[name])

--- snap ---

Now I tought I were able to let all methods of classes with DebugMeta as metaclass print out their arguments. But I got the following sad error:

TypeError: Error when calling the metaclass bases type 'function' is not an acceptable base type

That's a pity, isn't it? What could I do to get the above code to work? (No, I don't want to reimplement <type 'function'> without this unpleasant behaviour in Python.

Greetings, F. Sidler



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