[Python-Dev] concerns regarding callable() method (original) (raw)

Paul Pogonyshev pogonyshev at gmx.net
Sun Apr 8 14:10:32 CEST 2007

Hi,

I have seen in PEP 3100 that callable() function is planned to be removed in Python 3000 with this replacement: "just call the object and catch the exception???". For one, the object (if it is callable) can raise exception itself, so you need to somehow to differentiate between exception raised inside its call and exception raised if object is not callable to begin with.

Additionally consider something like

something.set_callback (x)

Assume that set_callback() wants to check if `x' is callable at all, to raise exception early and make error tracking easier. Currently, you can

assert callable (x)

But if callable() is removed, there is no apparent replacement. Of course, you cannot call `x' since it might have side-effects or be slow etc.

Please reconsider removal of callable() or provide an adequate replacement.

Paul

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