Path: utzoo!mnetor!uunet!husc6!hao!oddjob!gargoyle!ihnp4!cbosgd!mandrill!hal!ncoast!allbery
From: allbery@ncoast.UUCP (Brandon Allbery)
Newsgroups: comp.unix.wizards
Subject: Re: Command interfaces
Message-ID: <6870@ncoast.UUCP>
Date: 19 Dec 87 19:55:29 GMT
References: <432@cresswell.quintus.UUCP> <57900005@ccvaxa> <22179@ucbvax.BERKELEY.EDU>
Reply-To: allbery@ncoast.UUCP (Brandon Allbery)
Followup-To: comp.unix.wizards
Organization: Cleveland Public Access UN*X, Cleveland, Oh
Lines: 43

As quoted from <22179@ucbvax.BERKELEY.EDU> by bostic@ucbvax.BERKELEY.EDU (Keith Bostic):
+---------------
| In article <57900005@ccvaxa>, aglew@ccvaxa.UUCP writes:
| > Another reason not to use getopt: because it requires information to
| > be put in two places. You have to have a string containing your option
| > letters, and a case for the actual option. Bad design.
| 
| I am totally lost.  You want to explain how you're going to avoid having
| "information in two places"?
+---------------

You answered *this* one a bit earlier in your posting.  ("It doesn't get any
easier, _this_side_of_4th_GL's_."  Emphasis is mine.)

v---- note $ token in column 1 to trigger preprocessing

$		options (argc, argv) {
		/* usage is "[-b str]" */
		string option 'b' into foo:
		/* this option's usage is "[-c]" */
		boolean option 'c' into bar:
		    break;
		/* usage is "[-d mode]" */
		string option 'd' into baz as "mode":
		    if (strcmp(baz, "gorf") == 0) {
		        fprintf(stderr, "%s" -dgorf invalid\n");
		        exit(1);
		    }
		    break;
		}

Notice that type conversion and assignment is automatic; and, if necessary,
special processing can be performed.  I may actually write such a preprocessor;
it could collect the options and their arguments, and build a usage string
automatically.  By default any unmatched option would get the usage string and
exit, but a "default:" phrase could be used to allow special processing.
(Note:  I already *have* written some preprocessors of this general form, most
of them are for DBMS C hooks. It's not difficult for someone experienced with
lex/yacc.)
-- 
Brandon S. Allbery		      necntc!ncoast!allbery@harvard.harvard.edu
 {hoptoad,harvard!necntc,cbosgd,sun!mandrill!hal,uunet!hnsurg3}!ncoast!allbery
			Moderator of comp.sources.misc