[Python-3000] callable()

[Andrew Koenig]

I note in PEP 3000 the proposal to remove callable(), with the comment "just
call the object and catch the exception."

I think that's a bad idea, because it takes away the ability to separate the
callability test from the first call.  As a simple example, suppose you're
writing a function that you expect to be given a function as one of its
arguments:

	def foo(bar, fun):
		assert callable(fun)
		# ...

It might be that foo doesn't actually call fun until much later.
Nevertheless, from a testing viewpoint, it would be better to detect the
error immediately of passing something that can't be called.

If you didn't have callable, how would you write this example?