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

[Ferruh Yigit <ferruh.yigit@intel.com>]

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