Re: [PATCH v7 06/10] iotests: limit line length to 79 chars

[John Snow]

On 3/6/20 5:14 AM, Kevin Wolf wrote:
> Am 05.03.2020 um 19:25 hat John Snow geschrieben:
>> On 3/5/20 6:55 AM, Kevin Wolf wrote:
>>> Am 05.03.2020 um 00:14 hat John Snow geschrieben:
>>>>
>>>>
>>>> On 3/4/20 4:58 PM, Philippe Mathieu-Daudé wrote:
>>>
>>> Adding back the context:
>>>
>>>> -        sys.stderr.write('qemu-img received signal %i: %s\n' % 
>>>> (-exitcode, ' '.join(qemu_img_args + list(args))))
>>>> +        sys.stderr.write('qemu-img received signal %i: %s\n' % (
>>>> +            -exitcode, ' '.join(qemu_img_args + list(args))))
>>>
>>>>> Do we want to indent Python like C and align argument below opening
>>>>> parenthesis? Except when using sys.stderr.write() you seem to do it.
>>>>
>>>> This isn't an argument to write, it's an argument to the format string,
>>>> so I will say "no."
>>>
>>> The argument to write() is an expression. This expression contains the %
>>> operator with both of its operands. It's still fully within the
>>> parentheses of write(), so I think Philippe's question is valid.
>>>
>>>> For *where* I've placed the line break, this is the correct indentation.
>>>> emacs's python mode will settle on this indent, too.
>>>>
>>>> https://python.org/dev/peps/pep-0008/#indentation
>>>
>>> The PEP-8 examples are not nested, so it's not completely clear. I
>>> wonder if hanging indents wouldn't actually mean the following because
>>> if you line wrap an argument list (which contains the whole %
>>> expression), you're supposed to have nothing else on the line of the
>>> opening parenthesis:
>>>
>>>     sys.stderr.write(
>>>         'qemu-img received signal %i: %s\n'
>>>         % (-exitcode, ' '.join(qemu_img_args + list(args))))
>>>
>>
>> This is fine too.
>>
>>> But anyway, I think the question is more whether we want to use hanging
>>> indents at all (or at least if we want to use it even in cases where the
>>> opening parenthesis isn't already at like 70 characters) when we're
>>> avoiding it in our C coding style.
>>>
>>> There's no technical answer to this, it's a question of our preferences.
>>>
>>
>> Maybe it is ambiguous. Long lines are just ugly everywhere.
>>
>>>> (If anyone quotes Guido's belittling comment in this email, I will
>>>> become cross.)
>>>>
>>>>
>>>> But there are other places to put the line break. This is also
>>>> technically valid:
>>>>
>>>> sys.stderr.write('qemu-img received signal %i: %s\n'
>>>>                  % (-exitcode, ' '.join(qemu_img_args + list(args))))
>>>>
>>>> And so is this:
>>>>
>>>>     sys.stderr.write('qemu-img received signal %i: %s\n' %
>>>>                      (-exitcode, ' '.join(qemu_img_args + list(args))))
>>>
>>> PEP-8 suggests the former, but allows both styles:
>>>
>>> https://www.python.org/dev/peps/pep-0008/#should-a-line-break-before-or-after-a-binary-operator
>>>
>>
>> So in summary:
>>
>> - Avoid nested hanging indents from format operators
>> - Use a line break before the % format operator.
>> - OPTIONALLY(?), use a hanging indent for the entire format string to
>> reduce nesting depth.
> 
> Yes, though I don't think of it as a special case for format strings. So
> I would phrase it like this:
> 
> - Don't use hanging indent for any nested parentheses unless the outer
>   parentheses use hanging indents, too.
> - Use a line break before binary operators.
> - OPTIONALLY, use a hanging indent for the top level(s) to reduce
>   nesting depth.
> 
> The first one is the only rule that involves some interpretation of
> PEP-8, the rest seems to be its unambiguous recommendation.
> 
> Anyway, so I would apply the exact same rules to the following (imagine
> even longer expressions, especially the last example doesn't make sense
> with the short numbers):
> 
> * bad:
>     really_long_function_name(-1234567890 + 987654321 * (
>         1337 / 42))
> 
> * ok:
>     really_long_function_name(-1234567890 + 987654321
>                               * (1337 / 42))
> 
> * ok:
>     really_long_function_name(
>         -1234567890 + 987654321
>         * (1337 / 42))
> 
> * ok:
>     really_long_function_name(
>         -1234567890 + 987654321 * (
>             1337 / 42))
> 
>> e.g., either this form:
>> (using a line break before the binary operator and nesting to the
>> argument level)
>>
>> write('hello %s'
>>       % (world,))
>>
>>
>> or optionally this form if it buys you a little more room:
>> (using a hanging indent of 4 spaces and nesting arguments at that level)
>>
>> write(
>>     'hello %s'
>>     % ('world',))
>>
>>
>> but not ever this form:
>> (Using a hanging indent of 4 spaces from the opening paren of the format
>> operand)
>>
>> write('hello %s' % (
>>     'world',))
>>
>>
>>
>> yea/nea?
>>
>> (Kevin, Philippe, Markus, Max)
> 
> Looks good to me.
> 
> Kevin
> 

Great, thanks!

I am sorry for having been so tetchy. I appreciate the reviews.

--js