Guido> My point is that it's futile to use callable() -- even if it
Guido> passes, you have no assurance that you actually have a valid
Guido> callback. So why bother with it at all? It's counter to the
Guido> spirit of Python. If someone passes you a bad callback, they will
Guido> see a traceback when you call it. Then they fix their
Guido> program. That's how it's supposed to work.
There's one place where I find the traceback somewhat unhelpful. Consider
calling a method of a class with incorrect arguments:
>>> class C:
... def __init__(self):
... pass
...
>>> C(1)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: __init__() takes exactly 1 argument (2 given)
While in this example it's clear what method wasn't called correctly, a
callback called with the wrong number of arguments yields a fairly useless
stack trace. I'm thinking in particular of callbacks called from C code
(e.g. Gtk signal handlers). I think it would be helpful to check to see if
the function being called had an "im_class" attribute. If so, then resolve
the class name and include it in the TypeError message:
TypeError: C.__init__() takes exactly 1 argument (2 given)
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