Re: Org mode and Emacs

[Ihor Radchenko <yantar92@posteo.net>]

Richard Stallman <rms@gnu.org> writes:

>   > The way I see Org markup extension would make it easy to users add new
>   > custom markup, as needed. Then, no frequent changes to the base markup
>   > will be necessary to accommodate for less common use cases.
>
> I see a possible ambiguity and point of confusion.  When you say,
> "extension", do you mean "a package that gets loaded on top of
> ordinary Org mode"?  That's what I thought it meant.

A package or user Elisp snippet.

For example, Org currently allows extending hyperlinks like

     (defun org-man-export (link description format _)
       "Export a man page link from Org files."
       (let ((path (format "http://man.he.net/?topic=%s&section=all" link))
             (desc (or description link)))
         (pcase format
           (`html (format "<a target=\"_blank\" href=\"%s\">%s</a>" path desc))
           (`latex (format "\\href{%s}{%s}" path desc))
           (`texinfo (format "@uref{%s,%s}" path desc))
           (`ascii (format "%s (%s)" desc path))
           (t path))))

          (org-link-set-parameters "man" :export #'org-man-export)

Then, <man:emacs> links will be formatted arbitrarily during export.

The same idea will be for markup syntax:

@var{variable-name} will, in future, be defined as

    (org-markup-set-parameters "var" :export #'my-export-function-for-var)

@var is probably something we will have within Org, but if one needs
some weird markup for a specific manual, it will equally be possible to
define

@my-special-markup{contents}

via (org-markup-set-parameters "my-special-markup" :export #'custom-export-formatter)

> Implementing some of the Texinfo constructs in such a package, perhaps
> called org-texinfo, is an implementation detail as far as I'm
> concerned.
>
> But now I think maybe you mean something else -- that you propose
> to add some sort of limited macro definition facility and have the
> missing Texinfo constructs be defined using that.  Is that it?

We might allow in-document definitions like:

#+markup[html]: my-special-markup <foo>%s</foo>
#+markup[latex]: my-special-markup \foo{%s}
...

but the `org-markup-set-parameters' is what we preliminarily agreed upon
for now. Further features are to be discussed later.

> To be adequate for this job, the macro definition facility needs to be
> more powerful than they usually are.  The expansion of one construct
> needs to depend on the output format being generated, and sometimes
> the expansion of construct A depends on whether it is inside construct
> B.

> If the facility can do that, I think it will suffice for nearly all of
> the missing Texinfo constructs.  If you think of this as a method to
> simplify part of the implementation of Texinfo in Org, it may work.

Org is already capable to provide access to the full parse tree when
expanding links with custom :export function. The same can be done for
markup constructs. Much more difficult if one wants in-document
definitions though.

> But be prepared for exeptions, constructs that need special handling!
> If you think of this as a way to keep Org itself free of Texinfo
> impurities, it won't work.

May you elaborate about special handling?

-- 
Ihor Radchenko // yantar92,
Org mode contributor,
Learn more about Org mode at <https://orgmode.org/>.
Support Org development at <https://liberapay.com/org-mode>,
or support my work at <https://liberapay.com/yantar92>