[Python-Dev] Semantics of int(), index() (original) (raw)

Tres Seaver tseaver at palladion.com
Wed Apr 3 21:21:59 CEST 2013

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On 04/03/2013 01:50 PM, Ethan Furman wrote:

On 04/03/2013 10:46 AM, Barry Warsaw wrote:

On Apr 04, 2013, at 03:04 AM, Steven D'Aprano wrote:

On 04/04/13 01:16, Barry Warsaw wrote:

the other built-in types-as-functions, so int() calls int() which must return a concrete integer. Why must it? I think that's the claim which must be justified, not just taken as a given. When we call n = int(something), what's the use-case for caring that n is an instance of built-in int but not of a subclass, and is that use-case so compelling that it must be enforced for all uses of int() etc.? It's a consistency-of-implementation issue. Where built-in types are callable, they return concrete instances of themselves. This is true for e.g. list, tuple, dict, bytes, str, and should also be true of int.

Given that requirement, we still don't have to mandate that int return an actual instance of the int type: the coercion could happen inside int() (as it would for any non-subclass).

Tres. - --

Tres Seaver +1 540-429-0999 tseaver at palladion.com Palladion Software "Excellence by Design" http://palladion.com -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) Comment: Using GnuPG with undefined - http://www.enigmail.net/

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