Date: Wed, 26 Nov 2008 11:44:24 -0800 From: Tim Kientzle <kientzle@freebsd.org> To: Andrea Di Pasquale <spikey.it@gmail.com> Cc: freebsd-current@freebsd.org Subject: Re: Options handler for userspace programs Message-ID: <492DA718.60204@freebsd.org> In-Reply-To: <C529E93E-0463-4350-A4B9-39C731BD338E@gmail.com> References: <5D9F392B-97B5-4812-B5CB-047193715A94@gmail.com> <492C360B.8080304@freebsd.org> <C529E93E-0463-4350-A4B9-39C731BD338E@gmail.com>
next in thread | previous in thread | raw e-mail | index | archive | help
First, your --i example is a long option that happens
to be one letter. So that is handled by the existing
getopt_long() interface.
The -interface long option style is very rarely
used for a reason. In particular, it violates POSIX
conventions. For that reason, it is used almost
exclusively by a few applications (such as "find")
whose interfaces were standardized before POSIX.
That said, the getopt() API is not particularly
well-designed (the use of global variables is
particularly distasteful) and the getopt_long()
API is quite a mess. If you could come up with
something that had a nicer, easier-to-use API,
you might find some people interested in using it,
especially if it was very well-written,
easy-to-understand, and supported a wide variety
of command-line styles.
I would suggest you build this first to use in your
own projects and share it once you've used it in
several different programs. Only after you've used
it in a variety of different places will you be able
to be certain that you've covered all of the uses
that people are interested in. You should carefully
study the getopt_long() interface (which supports a
lot of variations), the POSIX standards, and the
historical command-line interfaces of programs
such as "dd", "tar", "cpio", and "find."
Here are some problems I have with getopt() and getopt_long():
* gzip supports command-line options in environment variables;
neither getopt() nor getopt_long() can be used to parse
a string containing command-line options
* dd uses "key=value" arguments (with no leading -); neither
getopt() nor getopt_long() supports this
* both use global variables, which limits how you can use them
* getopt_long() uses "magic letters" in the argument string
to change the behavior, which is poor API design (mixes
behavioral and parametric information in a single argument)
Have fun!
Tim
Andrea Di Pasquale wrote:
> Yes but getopt() and getopt() are limited. They can to handle
> only 2 options type, character and word. My idea is a main
> type that handle all. For example,
>
> Long options: Short options:
>
> interface i
> -interface -i
> --interface --i
>
> Both they can use one or two flag front the option. For example:
>
> optarg_t opts[] = {
> {"interface", "--i", OPT_REQARG1},
> {"--filter", "f", OPT_REQARG2},
> {"-typed", "t", OPT_REQOPT},
> {"-status", NULL, OPT_OPTARG1},
> {"status", "-s", OPT_OPTARG2},
> {NULL, "--v", OPT_NOARG},
> {"help", "h", OPT_NOARG},
> {NULL, NULL, OPT_NULL}
> };
>
> and optarg_t is:
>
> typedef enum optflag {
> OPT_NOARG, /* no arguments */
> OPT_REQARG1, /* required argument */
> OPT_REQARG2, /* required two arguments */
> OPT_REQOPT, /* required argument with 2° optional
> argument */
> OPT_OPTARG1, /* optional argument */
> OPT_OPTARG2, /* optional two arguments */
> OPT_NULL
> } optflag_t;
>
> typedef struct optarg {
> const char *opt_name; /* option's name */
> const char *opt_alias; /* option's alias */
> optflag_t opt_flag;
> } optarg_t;
>
> Thank you, regards
> Andrea
>
> Tim Kientzle wrote:
>
>> Have you looked at getopt_long, which is in the standard
>> FreeBSD C libraries?
>>
>> man 3 getopt_long
>>
>> The use of getopt() in most utilities instead of getopt_long()
>> is a very deliberate choice.
>>
>> Tim Kientzle
>>
>>
>> Andrea Di Pasquale wrote:
>>
>>> Hi! I seen that all freebsd' s programs use getopt() or sequence
>>> options with arguments.
>>> I wanna to propose new options handler that handle name or alias
>>> for options and
>>> option's argument, example no argument, required one or two
>>> arguments, required
>>> argument with 2° option argument and one or two optional arguments.
>>> Can it useful for freebsd?
>>> Regards,
>>> Andrea_______________________________________________
>>> freebsd-current@freebsd.org mailing list
>>> http://lists.freebsd.org/mailman/listinfo/freebsd-current
>>> To unsubscribe, send any mail to
>>> "freebsd-current-unsubscribe@freebsd.org "
>>
>>
>
> _______________________________________________
> freebsd-current@freebsd.org mailing list
> http://lists.freebsd.org/mailman/listinfo/freebsd-current
> To unsubscribe, send any mail to "freebsd-current-unsubscribe@freebsd.org"
>
>
>
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?492DA718.60204>