Re: [PATCH v3 3/3] branch: add '--no-name-prefix' option

[Junio C Hamano <gitster@pobox.com>]

"VALERI Yoann via GitGitGadget" <gitgitgadget@gmail.com> writes:

> -		OPT_STRING(0, "name-prefix", &name_prefix, N_("name"), N_("prefix for the branch to create")),
> +		OPT_STRING_F(0, "name-prefix", &name_prefix, N_("name"), N_("prefix for the branch to create"), PARSE_OPT_NONEG),
> +		OPT_BOOL(0, "no-name-prefix", &no_name_prefix, N_("do not use any prefix for the branch to create")),

You do not want a separate "no-*" entry in the options[] table.
If we look at parse-options.c to see how OPTION_STRING is handled,
we find:

	case OPTION_STRING:
		if (unset)
			*(const char **)opt->value = NULL;
		else if (opt->flags & PARSE_OPT_OPTARG && !p->opt)
			*(const char **)opt->value = (const char *)opt->defval;
		else
			return get_arg(p, opt, flags, (const char **)opt->value);
		return 0;

which tells us

 * "--no-name-prefix" is caught by "if (unset)" and causes the
   name_prefix variable set to NULL.

 * if we give OPT_OPTARG, we can allow "--name-prefix" (with no
   parameter) to default to opt->defval value; this feature is not
   very useful in our application.

 * Otherwise we get the string after "--name-prefix=".

So you do not need to do anything strange.  To correctly implement
the order of handling configuration and command line, you would do:

 * initialize name_prefix to NULL.  By default no name_prefix is
   used.

 * early in the cmd_branch() before you call parse_options(),
   consult the configuration and pick up branch.nameprefix
   and set it to name_prefix variable.

 * then you call parse_options().  If the command line has
   "--no-name-prefix", "if (unset)" kicks in and clears the
   name_prefix variable pointed at by the opt->value.  If the
   command line has "--name-prefix=blah", the name_prefix variable,
   which may have obtained a value from the configuration, is
   overwritten with "blah".  If the command line does not do
   anything, then the name_prefix variable will retain whatever
   value it got from the configuration.