Re: [dpdk-dev] [PATCH RFC] devtools: increase default line length to 100

[Andrew Rybchenko <arybchenko@solarflare.com>]

On 6/10/20 8:22 AM, Jerin Jacob wrote:
> On Tue, Jun 9, 2020 at 7:27 PM Bruce Richardson
> <bruce.richardson@intel.com> wrote:
>>
>> On Tue, Jun 09, 2020 at 04:40:28PM +0300, Andrew Rybchenko wrote:
>>> On 6/9/20 1:00 PM, Ananyev, Konstantin wrote:
>>>>
>>>>>
>>>>> On Mon, Jun 08, 2020 at 12:17:23PM -0700, Stephen Hemminger wrote:
>>>>>> On Mon,  8 Jun 2020 17:46:40 +0100 Bruce Richardson
>>>>>> <bruce.richardson@intel.com> wrote:
>>>>>>
>>>>>>> Rather than continuing to recommend an 80-char line limit, let's
>>>>>>> take a hint from the Linux kernel[1] and aim for an 100-char
>>>>>>> recommended limit instead.
>>>>>>>
>>>>>>> [1]
>>>>>>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=bdc48fa11e46f867ea4d75fa59ee87a7f48be144
>>>>>>>
>>>>>>> Signed-off-by: Bruce Richardson <bruce.richardson@intel.com> ---
>>>>>>> devtools/checkpatches.sh                 | 2 +-
>>>>>>> doc/guides/contributing/coding_style.rst | 2 +- 2 files changed, 2
>>>>>>> insertions(+), 2 deletions(-)
>>>>>>>
>>>>>>> diff --git a/devtools/checkpatches.sh b/devtools/checkpatches.sh
>>>>>>> index 158087f1c..4970ed830 100755 --- a/devtools/checkpatches.sh +++
>>>>>>> b/devtools/checkpatches.sh @@ -15,7 +15,7 @@
>>>>>>> VALIDATE_NEW_API=$(dirname $(readlink -f $0))/check-symbol-change.sh
>>>>>>> # Codespell can also be enabled by setting DPDK_CHECKPATCH_CODESPELL
>>>>>>> to a valid path # to a dictionary.txt file if dictionary.txt is not
>>>>>>> in the default location.
>>>>>>> codespell=${DPDK_CHECKPATCH_CODESPELL:-enable}
>>>>>>> -length=${DPDK_CHECKPATCH_LINE_LENGTH:-80}
>>>>>>> +length=${DPDK_CHECKPATCH_LINE_LENGTH:-100}
>>>>>>>
>>>>>>>  # override default Linux options options="--no-tree" diff --git
>>>>>>>  a/doc/guides/contributing/coding_style.rst
>>>>>>>  b/doc/guides/contributing/coding_style.rst index
>>>>>>>  4efde93f6..1db3a7bbe 100644 ---
>>>>>>>  a/doc/guides/contributing/coding_style.rst +++
>>>>>>>  b/doc/guides/contributing/coding_style.rst @@ -21,7 +21,7 @@ The
>>>>>>>  rules and guidelines given in this document cannot cover every
>>>>>>>  situation, so * In the case of creating new files, the style should
>>>>>>>  be consistent within each file in a given directory or module.  *
>>>>>>>  The primary reason for coding standards is to increase code
>>>>>>>  readability and comprehensibility, therefore always use whatever
>>>>>>>  option
>>>>> will make the code easiest to read.
>>>>>>>
>>>>>>> -Line length is recommended to be not more than 80 characters,
>>>>>>> including comments.  +Line length is recommended to be not more than
>>>>>>> 100 characters, including comments.  [Tab stop size should be
>>>>>>> assumed to be 8-characters wide].
>>>>>>>
>>>>>>>  .. note::
>>>>>>
>>>>>> I would even support going to 120 characters.
>>>>>>
>>>>>> Acked-by: Stephen Hemminger <stephen@networkplumber.org>
>>>>>
>>>>> I think 100 is enough.
>>>>>
>>>>> In my case, I have a 1080p 24" monitor, and with two terminals
>>>>> side-by-side 100 characters just fits inside each vim window. Going to
>>>>> 120 would be fine for single terminal at a time, but I would find
>>>>> awkward for e.g.  side-by-side diff comparison in meld etc.
>>>>
>>>> My preference would be to keep things as it is - 80 chars per line.
>>>> Having multiple different formatting styles in one source file looks
>>>> really awkward and make it hard to follow.
>>>
>>> +1
>>>
>> I wouldn't personally consider increasing the max line length as a style
>> change, but even if you consider it such I'd worry about rejecting style
>> changes on the basis that it may be different to what is there before. That
>> logic means that we can never, ever change any element of DPDK coding style.
>>
>> I can see the issue with changes that require us to rework the style of
>> code in order to comply with the new style, but changing the max length
>> from 80 to 100 does not make 80-char lines incorrect and needing changes.
> 
> Another point is: Other projects derived from the Linux kernel coding
> standard also
> getting migrated to the new coding standard. This change would be useful for:
> a) People works on multiple Linux coding standard derived projects

Valid point, but not really strong.
I think that .editorconfig solves it.

> b) Some of the code such as 'base' and 'common' code for HW drivers
> are shared between multiple projects.
> Such code needs adjustment/change when pulling to the DPDK code base
> it it still follows 80 chars per line.

Base and common code are not required to follow DPDK coding
style even now.