Re: generic color support for `texinfo.tex`

[Jean Abou Samra]

Le 20/12/2021 à 19:54, Patrice Dumas a écrit :
> On Mon, Dec 20, 2021 at 05:17:46PM +0100, Jean Abou Samra wrote:
> > Le 20/12/2021 à 17:01, Patrice Dumas a écrit :
> > > On Wed, Nov 24, 2021 at 03:17:22PM +0000, Werner LEMBERG wrote:
> > > > Hello Gavin,
> > > >
> > > >
> > > > For the LilyPond documentation we are going to use `pygments` to do
> > > > automatic colour highlighting of LilyPond snippets.  We also want to
> > > > support this feature in the PDF manuals.  To do so I ask you to apply
> > > > something like the following patch to make `@setcolor` work in
> > > > `@example` environments, too.
> > > I don't know if it is relevant or not, but, for HTML, there is an init
> > > file, tp/init/highligh_syntax.pm that uses source-highlight to highlight
> > > @example blocks based on the language argument.
> >
> > Thanks for the heads-up, I didn't know about that.
> > Unfortunately, it will not work for us, for several
> > reasons: first, we are still using texi2html, not
> > makeinfo (and even the decade-old texi2html 1.82!),
> That's indeed an issue...
>
> > and second, the highlighting is done by Pygments,
> > not by source-highlight.
> If it is possible to do something similar with Pygments than with 
> source-highlight
> it could easily be used as a replacement.  I do not know Pygments, some
> functionalities from source-highlight that could be absent from Pygments
> are a way to select fragments to be highlighted, as done with
> source-highlight --line-range option, and also something that could be
> unavailable could be something similar with source-highlight
> --range-separator option which is also used to be able to easily get the
> highlighted fragments.  However if those two functionalities are
> present, it should probably be pretty easy to be able to use Pygments
> too.


Thiking about it more, the main issue will be
how to call Pygments, which is a Python library.
Due to Python's interpreted nature, there is some
overhead of startup, around 0.05s -- which is
small, but starts to be noticeable if you have
hundreds of code snippets. If you find a way
to spawn a Python process and use the Python
API, that problem will be eliminated -- and it
will be trivial to implement equivalents to
--line-range and --range-separator. However, I
don't know about the implementation of makeinfo,
so I have no idea whether this kind of thing
is possible.

This is not problematic for us because our input
is already preprocessed by a Python script
(it's called lilypond-book and its main purpose
is to invoke LilyPond on the snippets and
insert @image commands).

Best,
Jean