for / while else doesn't make sense

[Steven D'Aprano]

On Sat, 21 May 2016 08:08 pm, Chris Angelico wrote:

> On Sat, May 21, 2016 at 7:56 PM, Steven D'Aprano <steve at pearwood.info>
> wrote:
>> On Sat, 21 May 2016 02:01 pm, Chris Angelico wrote:
>>
>>> On Sat, May 21, 2016 at 1:50 PM, Steven D'Aprano <steve at pearwood.info>
>>> wrote:
>>
>>>> Would you classify the second line here:
>>>>
>>>> print("Hello World!")
>>>> pass
>>>>
>>>>
>>>> as a bug? What exactly would your bug report be? "pass statement does
>>>> nothing, as expected. It should do nothing. Please fix."
>>>>
>>>
>>> Yes, I would. It's not a bug in Python or CPython - it's a bug in the
>>> second line of code there. It implies something that isn't the case.
>>
>> What do you think it implies?
>>
>> What part of the docs for "pass" implies this thing?
>>
>> help("pass"):
>>
>>     ``pass`` is a null operation --- when it is executed, nothing
>>     happens. It is useful as a placeholder when a statement is
>>     required syntactically, but no code needs to be executed, for
>>     example:  [examples snipped]
> 
> So why is a statement required syntactically after that print call?

Who said it was required?

The docs say that `pass` is useful when a statement is required, not the
other way: you can put `pass` anywhere a statement can go, without it being
required.


> Surely that implies something about the programmer's intent? It
> certainly isn't required according to the code you've shown me; and if
> someone submitted this code to me, I'd query it ("was there something
> else meant to be here?").

Sure. Does that make it a bug? I don't think so. I think that a linter
should flag it as unnecessary code, but the compiler certainly shouldn't
prohibit it. And a human reviewer might be able to judge whether it belongs
or not.

Some people might not like "FIXME" or "XXX" comments to flag missing code,
and use `pass` statements as placeholders. Who are we to tell them they
shouldn't?

I think we agree that it's not the compiler's job to enforce good coding
standards.




-- 
Steven