Re: [PATCH v2 2/3] diff: add -I<regex> that ignores matching changes

From: Michał Kępień <michal@isc.org>
Date: Oct 13, 2020, 06:38 UTC
Message-ID: <20201013063803.GD3278@larwa.hq.kempniu.pl>
In-Reply-To: <xmqqk0vvpbmp.fsf@gitster.c.googlers.com>

Show 8 quoted lines

> > +-I<regex>::
> 
> Since we are mimicking other folks' feature, giving also the
> 
> --ignore-matching-lines=<regex>
> 
> synonym to that their users are familiar with would be a good idea,
> no?

Some diff implementations (e.g. the OpenBSD one) lack the long option and I was aiming for the "greatest common divisor" for all diff implementations, but sure, I do not see how adding the synonym could hurt. I will do that in v3.

Show 24 quoted lines

> > @@ -5203,6 +5207,22 @@ static int diff_opt_patience(const struct option *opt,
> >  	return 0;
> >  }
> >  
> > +static int diff_opt_ignore_regex(const struct option *opt,
> > +				 const char *arg, int unset)
> > +{
> > +	struct diff_options *options = opt->value;
> > +	regex_t *regex;
> > +
> > +	BUG_ON_OPT_NEG(unset);
> > +	regex = xcalloc(1, sizeof(*regex));
> > +	if (regcomp(regex, arg, REG_EXTENDED | REG_NEWLINE))
> > +		die("invalid regex: %s", arg);
> > +	ALLOC_GROW(options->ignore_regex, options->ignore_regex_nr + 1,
> > +		   options->ignore_regex_alloc);
> > +	options->ignore_regex[options->ignore_regex_nr++] = regex;
> > +	return 0;
> > +}
> 
> Don't these parse-options callback functions have a way to tell the
> caller die instead of them themselves dying like this?  Would it
> work better to "return error(... message ...)", or would that give
> two error messages?

Yes, that would indeed look better, thanks - just one error message is generated when "return error(...)" is used. I just failed to notice that it is a thing. I will use it in v3.

Show 6 quoted lines

> In anycase, this is end-user facing, so we'd
> want it to be localizable, e.g.
> 
> 	die(_("invalid regexp given to -I: '%s'", arg));
> 
> probably.

Absolutely, I will fix that in v3. I tried to mimic what other similar code in the tree does and a quick `git grep 'die.*regex'` yielded mostly non-localized strings, so I settled for one as well.

-- 
Best regards,
Michał Kępień