[Python-Dev] PEP 7 and braces { .... } on if

[Guido van Rossum]

I interpret the PEP as saying that you should use braces everywhere but not
to add them in code that you're not modifying otherwise. (I.e. don't go on
a brace-adding rampage.) If author and reviewer of a PR disagree I would go
with "add braces" since that's clearly the PEP's preference. This is C
code. We should play it safe.

On Wed, May 31, 2017 at 9:02 AM, Serhiy Storchaka <storchaka at gmail.com>
wrote:

> 31.05.17 17:11, Victor Stinner пише:
>
> I have a question on the CPython coding code for C code, the PEP 7:
>> https://www.python.org/dev/peps/pep-0007/
>>
>> """
>> Code structure: (...); braces are strongly preferred but may be
>> omitted where C permits, and they should be formatted as shown:
>>
>> if (mro != NULL) {
>>      ...
>> }
>> else {
>>      ...
>> }
>> """
>>
>> This section was updated after the creation of CPython in 1991, so as
>> you may expect, a lot of existing C code doesn't respect this coding
>> style. I'm trying to slowly add "missing" braces and indent as the
>> example *when I have to modify existing code*.
>>
>> The problem is the "strongly preferred" and "omitted where C permits"
>> part. I would like to make the PEP 7 more explicit on that part since
>> in each review, I disagree with Serhiy who wants to omit them.
>> Example:
>>
>> if (func == NULL)
>>      return NULL;
>>
>> versus
>>
>> if (func == NULL) {
>>      return NULL;
>> }
>>
>> I now prefer the version with braces. It's more verbose, but it
>> prevents bugs when the code is modified later for whatever reasons.
>> IMHO it also makes the code easily to read and to understand.
>>
>> So I would suggest to modify the PEP 7 to *always* require braces for if.
>>
>> I would also suggest to require braces on "for(...) { ... }" and
>> "while(...) { ... }". But only if the code has to be modified, not
>> only to update the coding style.
>>
>
> Thank you for opening this discussion Victor. I was going to open it
> myself.
>
> I strongly prefer using braces around "for" and "while" bodies. I dislike
> unconditional adding braces, but after changing PEP 7 I became always
> adding them in my code and asking this in reviewed code. I even made
> Argument Clinic generating braces around gotos. But when I asked Barry to
> add braces around simple statements to satisfy PEP 7 requirements, he
> pointed out that braces are only "strongly preferred". Since that time I
> allowed myself to left braces out in cases when they look cluttering.
>
> I think that PEP 7 should be more explicit about cases in what braces are
> required and in what they are optional. I prefer to make them optional (or
> even make the variant without braces preferable) in case of "if" (without
> "else") or "case" body containing only the single "goto", "break",
> "continue" or simple "return". Especially if it follows by an empty line or
> closing brace. Adding braces in these cases decreases readability IMHO.
> This is one peculiarity for which many people like (or hate) Python.
>
>
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-- 
--Guido van Rossum (python.org/~guido)
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