Re: [O] [patch, ox] Unnumbered headlines

[Nicolas Goaziou]

Hello,

Rasmus <address@hidden> writes:

> True.  Personally, I find them nicer as you can just C-c C-c on your
> headline and write down some keyword that is typically easy to
> remember.  For properties I must rely on C-c C-x p — since the syntax
> is so awkward — and while it may be memorable to me try to explain it
> to co-authors who are not long-time Emacs users.
>
>> Another option is to use properties, e.g. "UNNUMBERED", or "NO_NUMBER"
>> with a non-nil value
>>
>>   * Some headline
>>     :PROPERTIES:
>>     :UNNUMBERED: t
>>     :END:
>>
>> It is harder to notice an unnumbered headline, but it doesn't add cruft
>> to the tag line, and this is far less important than :noexport:. This is
>> not perfect either, but I think the trade-off is honest.
>
> I can see you point, and I think I agree, though I personally much,
> much prefer tags.

Of course, tags are easier to use than properties, hence their
popularity. But they have some limitations, too.

I'm not saying that we must use a property, but this is definitely
something to ponder.

> Of course a utility function could be added (like the beamer minor
> mode) that adds the tag to give you a visual clue while the properties
> are really what matter.

Which would defeat the choice of using a property (i.e. avoid visual
clutter).

>> Another advantage is inheritance is already implemented for node
>> properties (see `org-export-get-node-property').
>
> Interesting.  I did not know.

Actually, it's not an "advantage" per se, since `org-export-get-tags'
does it too.

> The most elegant way would perhaps be to introduce in the output of
> `org-export-get-headline-number' whether a headline is unnumbered, but
> I am not sure how to do this without breaking the expected output of
> the function.
>
> A dirty fix might be add an extra 0 to the beginning of the section
> number list when dealing with unnumbered headings, but it is not so
> nice as the numbers loose their meaning. . .

Also, headline numbers can start with 0:

  ** H0.1
  * H1
  ** H1.1

You could add a 0 at the end instead, or begin with a negative number,
which cannot happen otherwise, but that would be hackish, for sure.

Since "ox-html.el", and possibly other back-ends, rely on
`number-to-string', there not much else to do down this road.

> What I am currently trying to do with ox-html is combining
> `org-export-get-headline-number' (which is always a list of numbers)
> and `org-export-numbered-headline-p' to determine if the ID should
> contain the substring "unnumbered".  Then the first unnumbered section
> would be "sec-unnumbered-1" and so forth.
>
>> The previous snippet from "ox-html.el" would become
>>
>>   (format "<span class=\"section-number-%d\">%d</span> "
>>           level
>>           (org-export-get-headline-id headline info))
>
> What I was experiment with is something like: 
>
> (format "<span class=\"section-number-%s-%d\">%d</span> "
>    (if numberedp "" "unumbered")
>    level)
>
> Do you think it would be better to work on
> `org-export-get-headline-id' and "solve" the issue in that way is a
> better approach than what I describe above?

Roughly, both approaches require the same amount of changes and imply
the same incompatibilities.

Nevertheless, I think it is cleaner for `org-export-get-headline-number'
to return nil when a headline is not numbered and to separate both
intents, i.e, provide a number and a unique internal id.

Anyway, feel free to experiment, there's no hurry.

Thanks for your work.


Regards,

-- 
Nicolas Goaziou