[Python-ideas] Bring back callable()

Chris Rebert pyideas at rebertia.com
Wed Nov 24 00:29:29 CET 2010

On Tue, Nov 23, 2010 at 3:01 PM, Antoine Pitrou <solipsis at pitrou.net> wrote:
> Hello,
> Python 3 has removed callable() under the justification that's it's not
> very useful and duck typing (EAFP) should be used instead. However,
> it has since been felt by many people that it was an annoying loss;
> there are situations where you truly want to know whether something is a
> callable without actually calling it (for example when writing
> sophisticated decorators, or simply when you want to inform the user
> of an API misuse).
> The substitute of writing `isinstance(x, collections.Callable)` is
> not good, 1) because it's wordier 2) because collections is really not
> an intuitive place where to look for a Callable ABC.
> So, I would advocate bringing back the callable() builtin, which was
> easy to use, helpful and semantically sane.

Perhaps it should also be renamed iscallable() for consistency with
isinstance() and issubclass() and to free up the nice name "callable"
for user use.


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