Re: [BUG] New exporter exports TOC twice

[Nicolas Goaziou <n.goaziou@gmail.com>]

Hello,

Carsten Dominik <carsten.dominik@gmail.com> writes:

>> The problem is that #+TOC cannot be a strict equivalent to
>> `org-export-with-toc', since the former cannot be introduced in the
>> document template.
>
> I am not sure I understand.  What do you mean?

A TOC keyword belongs to the contents of the document. On the other
hand, :with-toc is handled in a "template" function, which has access to
both the contents and the meta-data around it. Therefore, :with-toc can
insert a table of contents in more places than TOC.

For example, in latex back-end, TOC cannot insert a \tableofcontents
before \begin{document}, but toc:t can. Of course, this example doesn't
make sense as per LaTeX syntax, but it is possible that some other
back-end wants to allow this.

>> Also, this change would require each user back-end developer to check
>> for the presence of a TOC keyword with "headlines" value in the parse
>> tree when handling :with-toc property. This is not complicated, but
>> there are already many uncomplicated issues to think about when writing
>> a back-end.
>
> An alternative would be that the parser already makes this change.  Upon
> finding #+TOC, it would change the OPTION value in the parse tree.

The parser doesn't handle the OPTION keyword (it's just another
keyword), and neither should it (export options mustn't influence how
the parsing is done).

It belongs to the export framework to read export options and handle
them. Upon reading the with-toc value, it is indeed possible to check
for the presence of a TOC keyword in the parse tree.

However, in this case, I don't see the need to go out of our way just to
interpret differently what the user specified. Getting two tables of
contents is not surprising when you understand that "toc:t" and "#+TOC:
headlines" are independent ways of requesting a table of contents.


Regards,

-- 
Nicolas Goaziou