Re: Two trivial questions

[G. Branden Robinson]

At 2021-10-26T17:19:56-0700, Dale Snell wrote:
> On Tue, Oct 26, 2021 at 2:38 PM Peter Schaffter <peter@schaffter.ca> wrote:
> > Second question, maybe not so trivial.  Is it
> > acceptable to use a comma for decimal fractions that
> > are arguments to requests and macros (say .ps 12,5
> > instead of .ps 12.5) if a user's locale supports it?

I believe the answer is 'no'.

> That’s a very interesting question, but alas, I don’t
> know the answer.  Is groff written to pay attention to
> localization at all?  I don’t know.

GNU troff, the formatter, does call setlocale(3), but only to collect
the value of `LC_CTYPE` from the environment[1].

The parsing of numeric values, as far as I can tell, recognizes only a
dot as a decimal separator, and that only in arguments to requests and
escapes[2].  This seems like a sound choice to me to keep the input
language (not the language of the document text) consistent and
portable.  In general, groff, like troff before it, avoids non-integer
arithmetic.

Example:
$ groff -Tps -z
.tm \n[.ps]
10000
\s[10.25]
.tm \n[.ps]
10250
.ps 8.75z
.tm \n[.ps]
8750

Regards,
Branden

[1] 
https://git.savannah.gnu.org/cgit/groff.git/tree/src/roff/troff/input.cpp#n8019
[2] 
https://git.savannah.gnu.org/cgit/groff.git/tree/src/roff/troff/number.cpp#n490
    
https://git.savannah.gnu.org/cgit/groff.git/tree/src/roff/troff/number.cpp#n490

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