Re: [dpdk-dev] [PATCH] doc/contributing/documentation: add info about including code

["Burakov, Anatoly" <anatoly.burakov@intel.com>]

On 04-May-21 12:56 PM, Thomas Monjalon wrote:
> 04/05/2021 13:15, Ferruh Yigit:
>> On 5/4/2021 11:44 AM, Thomas Monjalon wrote:
>>> 04/05/2021 12:35, Ferruh Yigit:
>>>> On 5/4/2021 10:59 AM, Thomas Monjalon wrote:
>>>>> 04/05/2021 11:32, Burakov, Anatoly:
>>>>>> On 03-May-21 10:02 PM, Thomas Monjalon wrote:
>>>>>>> 21/04/2021 11:11, Conor Walsh:
>>>>>>>> +  The following will include a snippet from the skeleton sample app::
>>>>>>>> +
>>>>>>>> +      .. literalinclude:: ../../../examples/skeleton/basicfwd.c
>>>>>>>> +        :language: c
>>>>>>>> +        :start-after: Display the port MAC address.
>>>>>>>> +        :end-before: Enable RX in promiscuous mode for the Ethernet device.
>>>>>>>> +        :dedent: 1
>>>>>>>
>>>>>>> I would prefer indenting the options with 3 spaces
>>>>>>> to make them aligned with literalinclude.
>>>>>>>
>>>>>>> [...]
>>>>>>>> +* ``start-after`` and ``end-before`` can use any text within a given file,
>>>>>>>> +  however it may be difficult to find unique text within your code to mark the
>>>>>>>> +  start and end of your snippets. In these cases, it is recommended to include
>>>>>>>> +  explicit tags in your code to denote these locations for documentation purposes.
>>>>>>>> +
>>>>>>>> +  This can be done as follows:
>>>>>>>> +
>>>>>>>> +  .. code-block:: c
>>>>>>>> +
>>>>>>>> +    /* #guide_doc: Example feature being documented. */
>>>>>>>> +    ...
>>>>>>>> +    /* #guide_doc: End of example feature being documented. */
>>>>>>>
>>>>>>> I think we can standardize this usage in a beautiful syntax.
>>>>>>> My proposal, using the scissor sign:
>>>>>>>
>>>>>>>       /* Foo bar >8 */
>>>>>>>       foo(bar);
>>>>>>>       /* 8< End of foo bar */
>>>>>>>
>>>>>>>       .. literalinclude:: foobar.c
>>>>>>>          :language: C
>>>>>>>          :start-after: Foo bar >8
>>>>>>>          :end-before: 8< End of foo bar
>>>>>>>
>>>>>>> Another idea:
>>>>>>>
>>>>>>>       /*~ Foo bar */
>>>>>>>       foo(bar);
>>>>>>>       /*~ End of foo bar */
>>>>>>>
>>>>>>>       .. literalinclude:: foobar.c
>>>>>>>          :language: C
>>>>>>>          :start-after: ~ Foo bar
>>>>>>>          :end-before: ~ End of foo bar
>>>>>>>
>>>>>>> Maybe we don't need any markup for the start line and keep it natural:
>>>>>>>
>>>>>>>       /* Foo bar */
>>>>>>>       foo(bar);
>>>>>>>       /* end: Foo bar */
>>>>>>>
>>>>>>>       .. literalinclude:: foobar.c
>>>>>>>          :language: C
>>>>>>>          :start-after: Foo bar
>>>>>>>          :end-before: end: Foo bar
>>>>>>
>>>>>> Not having markup will 1) risk people accidentally "fixing" or otherwise
>>>>>> modifying comments, and 2) has bigger potential for collisions elsewhere
>>>>>> in the comments. While these aren't big risks, IMO it should be
>>>>>> explicitly obvious that a comment is not just a comment but a marker docs.
>>>>>>
>>>>>> Having named tags like in the original proposal is the most explicit
>>>>>> version of the above, which is why i favor it, but i think it's OK to
>>>>>> have a lighter-weight syntax (e.g. with scissors for example), however i
>>>>>> don't think it's a good idea to leave things implicit like your last
>>>>>> suggestion.
>>>>>
>>>>> I think the first comment is not only for code extraction,
>>>>> but also for code reader, that's why I think it's good to keep it natural.
>>>>
>>>> +1 to Anatoly's comment, to make it obvious to the reader of the code that the
>>>> comment is used for documentation purposes and use explicit syntax for it.
>>>
>>> So you assume the comment is only for doc extraction?
>>> I think it can be a real comment, otherwise we'll need to have
>>> 2 lines: 1 for doc extraction, 1 for code comment.
>>>
>>
>> I see your point, for the cases that there is already a comment before (or
>> after) the code, will it be too bad to have multiple lines, something like:
>>
>> /* Actual comment
>>   * More details
>>   *
>>   * explicit marker */
>>
>>
>> I think explicit marker has the advantage of:
>> - Whoever updating the comment will know that it is a marker for the
>> documentation and be careful on update
>> - Whoever updating the code between the markers, know that it may be required to
>> re-visit the relevant documentation and update it because of code change
>> - Whoever reading the code will know that part is in a documentation, and may be
>> interested to go and check the relevant documentation
>> - Whoever reading the code, and not very familiar with DPDK convention, still
>> can understand what that comment is for and benefit from above
> 
> I understand these points.
> But I'm afraid the proposed syntax #guide_doc:
> is not so obvious for everybody.
> 
> I'm sure there can be a better syntax.
> 

I'm not particularly attached to either syntax, as long as it's clearly 
documented and explicitly visible in the code (as opposed to something 
that kinda-sorta-but-doesn't-really-look-like-a-marker type syntax).

So, we'd have to give up some "natural-ness", as *that's the point* of 
having a syntax. And i'm certainly OK with comment style like this:

/*
  * some meaningful comment.
  * :doc_marker:
  */
...
/* :end doc_marker: */

Or something to that effect. What i'm *not* in favor of is these markers 
looking like part of a comment, rather than markers for doxygen.

-- 
Thanks,
Anatoly