On 5/12/2015 9:56 AM, Steven D'Aprano wrote:
The consensus among the core developers is:
* in general, the harm and inconvenience from accidentally
shadowing built-ins is not great, and it usually easy to
spot, debug and prevent;
* when it comes to built-in functions (e.g. sum, map, pow)
and types (e.g. int, str, list) there are significant and
important use-cases for allowing shadowing;
(e.g. the built-in sum function shouldn't prevent other
modules from providing their own sum function)
* but when it comes to None, True and False, there are no
significant or important use-cases for shadowing (it is
almost always a bug, not a feature, to redefine None).
The general principle here is of consenting adults: Python allows you to
shadow built-ins because sometimes it is useful, and the good outweighs the
potential harm. There are a handful of exceptions to that general principle
(e.g. None, True, False, I can't think of any others) because in those
cases the harm (as tiny as it is) outweighs the good.
Having followed Python development for 18 years, I think this is a fair
summary.
--
Terry Jan Reedy
--
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