[TUHS] Systematic approach to command-line interfaces [ meta issues ]

John Cowan cowan at ccil.org
Mon Aug 2 07:30:19 AEST 2021

On Sun, Aug 1, 2021 at 3:48 PM <arnold at skeeve.com> wrote:

> I happen to like the getopt_long interface designed by the GNU
> project. It's easy to learn, setup and use. Once it's in place
> it's set and forget.

I agree, and what is more, I say, it is a grammar already, if a simple
one.  You declare what you accept and what's to be done, making it a DSL
expressed as an array of structs.

The only thing it lacks is that old getopt is a bag on the side rather than
being integrated: struct option should have an additional member "char
short_option", where '\0' means "no short option".  Given that feature and
three per-program values "progname" (argv[0] by default), "version", and
"usage_string", the --version and --help options can be processed inside
getopt itself.  I especially like that you pass per-option pointers saying
where to put the value, so no case statement required, just create some
global or local variables and pass in their addresses.  Automatic support
for "--nofoo" given "--foo" would be good as well.
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