Re: Warn about long lines

[Alejandro Colomar]

Hi Branden,

On 8/27/22 20:02, G. Branden Robinson wrote:
> Hi Alex,
>
> At 2022-08-27T19:42:43+0200, Alejandro Colomar wrote:
> > Lines with highlighting have more characters than visible.  Of course,
> > in my 80 limit, I only want to count visible ones, so I need to get
> > rid of the highlighting.  I started with using [[:print:]] in grep(1),
> > but it also counted part of the multibyte sequences of the
> > highlighting (i.e., it didn't count the character that introduced the
> > escape sequence, but counted the rest; more or less, what you'd see if
> > you run less without -R; e.g., '[1m').  So I used this, as a big
> > cannon; probably shooting more than necessary; I wanted to make sure
> > no traces remained.
>
> At some point you're going to hit the problem of printable UTF-8
> sequences that occupy more than one byte but only one character cell.

Hitted.  Heh!  Boxed tables.  Fixed with -Tascii.

> > Although in this case it's for running groff(1)'s warnings, for which
> > I'll need to run groff(1).
>
> No, you're not running it for groff(1)'s warnings, you're running it for
> the formatter's warnings.  The formatter is troff(1) and groff(1) always
> runs it.

Makes sense.  Good to know.  So, I prefer the explicit pipeline, so I 
know what really is going on.  I hope this will improve the quality of 
my bug reports, and my debugging abilities.

> > Do I get the same warnings by passing -ww and -rCHECKSTYLE=3 to
> > troff(1) and to groff(1)?  or does groff(1) have extra warnings (maybe
> > since it also has access to the tbl(1) input)?
>
> Slow down there.  groff itself has only one warning.
>
>    warning("-TXps option is obsolete: use -X -Tps instead");
>
> https://git.savannah.gnu.org/cgit/groff.git/tree/src/roff/groff/groff.cpp#n315
>
> It also has a few error diagnostics because it attempts to locate the
> 'DESC' file for the output device and from there determine what
> preprocessor (if any) and posprocessor it needs to run.
>
> None of this has to do with the content of your document.

Good to know.

> > > The data between troff(1) and grotty(1), or any other post-processor,
> > > is in groff_out(5) format and what marks to put where has already been
> > > decided, fixing the line length.
> > >
> > > The man macros realise the man command might be on a terminal of varying
> > > width or producing ‘cat’ man pages for storage.  To allow the man
> > > command to specify the line-length required, the man macro allows the LL
> > > number register to override what length it would normally use for the
> > > ‘.ll’ command.  When the man command runs troff, it uses the -r option
> > > to set the number register.
> > >
> > > > It doesn't seem like a man(7)-specific thing
> > >
> > > It is.
>
> Only sort of.  Registers for setting line length, page offset, page
> length, and vertical spacing trickled into the various macro packages in
> an inconsistent way over the years.
>
> One of the post-1.23 projects I have in mind is to complete the set for
> all macro packages and teach nroff about them so I can do something
> highly satisfying: give nroff an option to auto-size output to the
> terminal dimensions.
>
> > > > I mean, when searching for an option that controls the line
> > > > length, I expect it to be a generic option that will be applicable
> > > > to groff as a whole
>
> This was not thought to be necessary in the 1970s, because the media
> dimensions were rigidly fixed for Teletype devices and even on the
> C/A/T, you had to physically cut the giant roll of "paper" into leaves
> yourself.

:)

[...]

> > Ahh, it makes sense: normally documents are designed to be rendered in
> > a specific device and characteristics.  It's only manual pages that
> > are more generic in that regard, in that they are mostly read in
> > terminals (not their original conception, but that's what it is right
> > now).
>
> We could have more flexibility than we do.  I began realizing this when
> I started working on the ms.ms document.
>
> > > groff(1) is a confusing front-end program for the normal troff-based
> > > pipeline so some more interesting options would be in troff(1), for
> > > example.  But in this case, it's not a command-line option.  :-)
>
> -rLL=XXn is very much a groff(1) command line option (that gets passed
> to troff(1)) and I have used it for years in my own little shell
> function.
>
> $ type gman
> gman is a function
> gman ()
> {
>      local width=$(stty size | cut -d' ' -f2);
>      width=$(( width - 1 ));
>      local cmd=$(./build/grog -Tutf8 -b -ww -P-i -rU1 -rLL=${LL:-$width}n "$1");
>      ./build/test-$cmd | less -R
> }

This width - 1 is a workaround for the issue I saw, but different from 
what man(1) does.  I wonder why all these workarounds exist.

Cheers,

Alex

> Regards,
> Branden

--
Alejandro Colomar
<http://www.alejandro-colomar.es/>

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