[Python-Dev] concerns regarding callable() method

Guido van Rossum guido at python.org
Sun Apr 8 17:55:26 CEST 2007

On 4/8/07, Paul Pogonyshev <pogonyshev at gmx.net> wrote:
> Guido van Rossum wrote:
> > What if someone passes a callable that doesn't have the expected signature?
> Well, I don't know a way to catch such situations now, so removing
> callable() will not make it worse (even if you don't know about hasattr
> trick above.)

My point is that it's futile to use callable() -- even if it passes,
you have no assurance that you actually have a valid callback. So why
bother with it at all? It's counter to the spirit of Python. If
someone passes you a bad callback, they will see a traceback when you
call it. Then they fix their program. That's how it's supposed to

--Guido van Rossum (home page: http://www.python.org/~guido/)

More information about the Python-Dev mailing list