[Python-ideas] Should Python have user-defined constants?

Stéfane Fermigier sf at fermigier.com
Tue Nov 21 05:40:14 EST 2017

On Tue, Nov 21, 2017 at 11:03 AM, Serhiy Storchaka <storchaka at gmail.com>

> 21.11.17 11:34, Saeed Baig пише:
>> Serhiy asked, in relation to constants, “To do what? What problem do you
>> need to solve?”. No problem in particular, to be honest. I just thought
>> they’d be nice since they’d increase confidence that my
>> variables-intended-to-be-constants wouldn’t get reassigned, and just to
>> increase readability/explicitness to other programmers.
> For increasing readability/explicitness you can use a name convention
> (UPPER_CASE), comments and documentation.

UPPER_CASE variable names are a reasonable convention for global constants.

I wouldn't like to read something like:

for i in range(0, 100):
   FOO = f(i)
   BAR = g(i, FOO)

but rather:

for i in range(0, 100):
   const foo = f(i)
   const bar = g(i, foo)


for i in range(0, 100):
   let foo = f(i)
   let bar = g(i, foo)

If we move on with this idea (which is a long shot of course), choosing
between 'let' and 'const' is a matter of taste and being consistent with
other languages.

As for increasing confidence that your variables-intended-to-be-constants
> wouldn’t get reassigned, you can use read-only properties. This is a tricky
> to implement read-only properties for modules, but see PEP 562 which should
> help to do this.
> Please don't use GIGANTIC font in your messages.



> And please don't create a new thread when answer.
> And *please* don't include unrelated text in your messages.
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Founder & CEO, Abilian - Enterprise Social Software -
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“You never change things by fighting the existing reality. To change
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Buckminster Fuller
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