Re: [groff] Of grog, preprocessors, and missing programs

[John Gardner]

> loadVersion()'s regexp can be simplified because `xx*' is `x+'.  :-)

Well-spotted refactoring error, thank you. ;-)

> I didn't read all the way through that page and ended up skimming it.
> You use grog if it's available, falling back on your own logic to
> analyse the troff source.

The fallback was necessitated because Fedora's Groff ships without a
grog(1).

> What's the problem with grog suggesting something that isn't installed?

Rendering needs to succeed even if the necessary preprocessors aren't
installed; the adapter makes sure to call Groff without options it knows
are unsupported. This is a setting where an incorrect rendering is more
tolerable than *no* rendering whatsoever; hence the song-and-dance routine.


On Fri, 9 Aug 2019 at 19:08, Ralph Corderoy <address@hidden> wrote:

> Hi John,
>
> > I've noticed that grog(1) will suggest options for preprocessors
> > irrespective of whether they're even available on the user's system.
>
> That seems fair enough.  The rest of the system is used to being asked
> to run programs that don't exist and report that to the user in a
> familiar manner.
>
> > The problem is when users aren't Troff-savvy, and document formatting
> > is performed by a GUI without user intervention. That's exactly half
> > of what Roff.js <https://github.com/Alhadis/Roff.js> exists to do —
> > the code talking to Groff
> > <
> https://github.com/Alhadis/Roff.js/blob/8678ef365626e049c58b4ad65d62383fe7db49b9/lib/adapters/troff/groff.mjs
> >
> > from the browser is substantially more complex than it should be, due
> > to the translation layers involved...
>
> loadVersion()'s regexp can be simplified because `xx*' is `x+'.  :-)
>
> I didn't read all the way through that page and ended up skimming it.
> You use grog if it's available, falling back on your own logic to
> analyse the troff source.  Either way, you check the resulting guesses
> against what's available:
>
> https://github.com/Alhadis/Roff.js/blob/8678ef365626e049c58b4ad65d62383fe7db49b9/lib/adapters/troff/groff.mjs#L575
> What's the problem with grog suggesting something that isn't installed?
>
> --
> Cheers, Ralph.
>
>