"None" and "pass"

[Chris Angelico]

On Tue, Feb 6, 2018 at 6:47 AM, Alain Ketterlin
<alain at universite-de-strasbourg.fr.invalid> wrote:
> ram at zedat.fu-berlin.de (Stefan Ram) writes:
>
>>   A participant of my Python course asked whether one could
>>   also use "None" instead of "pass". What do you think?
>>
>> def f():
>>     pass
>>
>>   can also be written as
>>
>> def f():
>>     None
>>
>>   . Is there any place where "None" could not be used
>>   instead of "pass"?
>
> No, an expression is always a valid statement:
>
>     https://docs.python.org/3.6/reference/simple_stmts.html
>
> Use None, or 42+0, or 1+1+1+1+1+1+1+1+1, or whatever you want (that does
> not have any side-effect and/or throw an exception). And be fired right
> after your first code review.
>

As one special case, I would accept this sort of code:

def f():
    ...

(three dots representing the special value Ellipsis)

It's a great short-hand for "stub".

Otherwise, though, an expression that isn't used (like putting "1+1"
on a line on its own) should normally fail a code review.

ChrisA