7.3 Quick Start

Since it is generally easier to start with a simple example than it is to look at the options that AutoGen uses itself, here is a very simple AutoOpts example. You can copy this example out of the Info file and into a source file to try it. You can then embellish it into what you really need. For more extensive examples, you can also examine the help output and option definitions for the commands columns, getdefs and autogen itself.

For our simple example, assume you have a program named check that takes two options:

1. A list of directories to check over for whatever it is check does. You want this option available as a POSIX-style flag option and a GNU long option. You want to allow as many of these as the user wishes.
2. An option to show or not show the definition tree being used. Only one occurrence is to be allowed, specifying one or the other.

First, specify your program attributes and its options to AutoOpts, as with the following example.

AutoGen Definitions options;
prog-name     = check;
prog-title    = "Checkout Automated Options";
long-opts;

main = { main-type = shell-process; };

flag = {
    name      = check-dirs;
    value     = L;        /* flag style option character */
    arg-type  = string;   /* option argument indication  */
    max       = NOLIMIT;  /* occurrence limit (none)     */
    stack-arg;            /* save opt args in a stack    */
    descrip   = "Checkout directory list";
};

flag = {
    name      = show_defs;
    descrip   = "Show the definition tree";
    disable   = dont;     /* mark as enable/disable type */
                          /* option.  Disable as `dont-' */
};

Then perform the following steps:

1. cflags="-DTEST_CHECK_OPTS `autoopts-config cflags`"
2. ldflags="`autoopts-config ldflags`"
3. autogen checkopt.def
4. cc -o check -g ${cflags} checkopt.c ${ldflags}
5. ./check --help

Running those commands yields:

check - Checkout Automated Options
USAGE:  check [ -<flag> [<val>] | --<name>[{=| }<val>] ]...
  Flg Arg Option-Name    Description
   -L Str check-dirs     Checkout directory list
                                - may appear multiple times
      no  show-defs      Show the definition tree
                                - disabled as --dont-show-defs
   -? no  help           Display usage information and exit
   -! no  more-help      Extended usage information passed thru pager

Options are specified by doubled hyphens and their name
or by a single hyphen and the flag character.

Normally, however, you would compile `checkopt.c' as in:

cc -o checkopt.o -I$prefix/include -c checkopt.c

and link `checkopt.o' with the rest of your program. The main program causes the options to be processed by calling optionProcess (see section optionProcess):

main( int argc, char** argv )
{
  {
    int optct = optionProcess( &checkOptions, argc, argv );
    argc -= optct;
    argv += optct;
  }

The options are tested and used as in the following fragment. "ENABLED_OPT" is used instead of "HAVE_OPT" for the show-defs option because it is an enabled/disabled option type:

  if (  ENABLED_OPT( SHOW_DEFS )
     && HAVE_OPT( CHECK_DIRS )) {
    int    dirct = STACKCT_OPT( CHECK_DIRS );
    char** dirs  = STACKLST_OPT( CHECK_DIRS );
    while (dirct-- > 0) {
      char* dir = *dirs++;
      ...

A lot of magic happens to make this happen. The rest of this chapter will describe the myriad of option attributes supported by AutoOpts. However, keep in mind that, in general, you won't need much more than what was described in this "quick start" section.

This document was generated by Bruce Korb on September, 30 2006 using texi2html 1.76.