Re: [O] Overriding org-html-headline or other export functions?

[Charles C. Berry]

On Mon, 29 May 2017, Brett Viren wrote:

> "Charles C. Berry" <address@hidden> writes:
>
> > You do have that wrong.  This is exactly what export filters and
> > derived backends are for.  In fact, you can use both.  For an example,
> > see
> >
> > http://orgmode.org/worg/exporters/filter-markup.html
> >
> > You will want to change `latex' to `html' in the
> >
> >         `(org-export-define-derived-backend ...)'
> >
> > call and delete all filters except for `:filter-headline'.  And revise
> > `ox-mrkup-filter-headline' accordingly.
>
> Thanks for checking me on this, but I still don't see it.
>
> If I understand, a derived HTML backend with my own filter-headline
> would let me add my own extra HTML *outside* the "<h1>...</h1>",
> "<h2>...</h2>", etc, HTML that is generated by the base
> org-html-headline filter.  But for the output I want I need to add my
> extra HTML *inside* the contents of the "<hN>...</hN>" tags.  And I
> don't see an export filter for this "..." part.
>
> Or, maybe you suggest I do direct "surgery" on the TEXT argument that
> gets passed in to the filter and insert the "..." that way?  I guess it
> could work to find the end of the "<hN...>" opening tag and then insert
> my "..." part.  I'll try this approach.
Yeah. You can use one or two `replace-regexp-in-string' calls I think.

You get that if the underlying code in ox-html changes in a way that is 
incompatible with your headline transcoder, you will have to start over. 
OTOH, since you only change one line it would not be the end of the world 
unless lots of others depend on that code and you were enjoying a 
wilderness vacation.  I would guess that such changes would be few at 
this late date.

If this is something you only use for personal work, then

#+BEGIN_SRC emacs-lisp
(org-export-define-derived-backend 'bv 'html
  :translate-alist '((headline . org-bv-headline)))
(defun org-bv-headline <your function here>)
#+END_SRC

finishes the job without a lot of fuss.

HTH,

Chuck