Re: [groff] Work-related rants

[Ingo Schwarze]

Hi John,

John Gardner wrote on Mon, Dec 17, 2018 at 02:33:25AM +1100:

> I really do wish Mandoc would support the Troff intermediate
> output format.

I just had a brief look again at your message "Formal AST output
in mandoc" from January 16, and the ensuing thread, to refresh my
memory.  IIUC, you are working on a JavaScript program in the context
of some gigantic heavy-weight framework to render manual pages in
real time on a canvas while an author is editing them.  Corrrect
me if i got that wrong...

If groff is installed on the system, taking groff_out(5) as the
input format for your program looks like a possible choice.

On a system where you use mandoc(1) for rendering, you should really
use the mandoc -Thtml output as your input format.  Mandoc PDF
output is just not good enough for anything except casual human
viewing, in particular nor for automated postprocessing.

Even if a -Tgroff output mode were written, it seems to me you
would still be better off using -Thtml rather than -Tgroff because
in -Tgroff, all the information about semantic functions (class
attributes in HTML parlance) would be lost.

Even if i'm overlooking something and -Tgroff would be better for
your particular purpose (if so, why?), and even if you were to
write the -Tgroff output mode, i would hesitate to include it; it
seems too much of a niche application to warrant the resulting
maintenance effort: i fail to imagine any other use case
where -Tgroff might help...

> Even if processing text piped between programs isn't nearly as
> efficient as reading it from a compiled program, it's so much
> more flexible.

I'm not sure i get the point here.  You certainly don't want to
compile the mandoc parser and directly link your program to it
because the syntax tree structs are not stable, but constantly
evolving.  Besides, pipes do seem quite efficient to me - you aren't
really worried about the copyin/copyout overhead in the kernel, or
are you?  Can't really believe that's what you are trying to say
while on the other hand you are using monstrous frameworks like
electron/atom/js/whatever...

So to me, the question doesn't seem to be efficiency of pipes vs.
direct memory access, but rather which communication format to use:
HTML, UTF-8 text, PostScript in order of decreasing mandoc output
quality, and -Tgroff only if there are strong arguments that i
haven't heard or understood yet.

Yours,
  Ingo