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7.5.10 Automatically Supported Options

AutoOpts provides automated support for several options. help and more-help are always provided. The others are conditional upon various global program attributes being defined See Program Description Attributes.

Below are the option names and default flag values. The flags are activated if and only if at least one user-defined option also uses a flag value. The long names are supported as option names if long-opts has been specified. These option flags may be deleted or changed to characters of your choosing by specifying xxx-value = "y";, where xxx is one of the option names below and y is either empty or the character of your choice. For example, to change the help flag from ? to h, specify help-value = "h";; and to require that save-opts be specified only with its long option name, specify save-opts-value = "";.

Additionally, the procedure that prints out the program version may be replaced by specifying version-proc. This procedure must be defined to be of external scope (non-static). By default, the AutoOpts library provides optionPrintVersion and it will be the specified callback function in the option definition structure.

With the exception of the load-opts option, none of these automatically supported options will be recognized in configuration files or environment variables.

‘help -?’

This option will immediately invoke the USAGE() procedure and display the usage line, a description of each option with its description and option usage information. This is followed by the contents of the definition of the detail text macro.

‘more-help -!’

This option is identical to the help option, except that the output is passed through a pager program. (more by default, or the program identified by the PAGER environment variable.)

‘usage -u’

This option must be requested by specifying, usage-opt in the option definition file. It will produce abbreviated help text to stdout and exit with zero status (EXIT_SUCCESS).

‘version -v’

This will print the program name, title and version. If it is not followed by anything or is followed by the letter v, just the program name and version will be printed. If followed by the letter c and a value for copyright and owner have been provided, then the copyright will be printed, too. If it is followed by the letter n, then the full copyright notice (if available) will be printed. The version attribute must be specified in the option definition file.

Because some target platforms discourage optional arguments to options, the autoopts library can be compiled with NO_OPTIONAL_OPT_ARGS defined. Alternatively, the version-type attribute can be added to the option definitions and it can specify which flavor is preferred. In either case, an argument to the --version option will then be disallowed.

‘load-opts -<’ ¶

This option will load options from the named file. They will be treated exactly as if they were loaded from the normally found configuration files, but will not be loaded until the option is actually processed. This can also be used within another configuration file, causing them to nest. This is the only automatically supported option that can be activated inside of config files or with environment variables.

Specifying the negated form of the option (--no-load-opts) will suppress the processing of configuration files and environment variables.

This option is activated by specifying one or more homerc attributes.

‘save-opts ->’ ¶

This option will cause the option state to be printed in the configuration file format when option processing is done but not yet verified for consistency. The program will terminate successfully without running when this has completed. Note that for most shells you will have to quote or escape the flag character to restrict special meanings to the shell.

The output file will be the configuration file name (default or provided by rcfile) in the last directory named in a homerc definition.

This option may be set from within your program by invoking the "SET_OPT_SAVE_OPTS(filename)" macro (see SET_OPT_name - Force an option to be set). Invoking this macro will set the file name for saving the option processing state, but the state will not actually be saved. You must call optionSaveFile to do that (see optionSaveFile). CAVEAT: if, after invoking this macro, you call optionProcess, the option processing state will be saved to this file and optionProcess will not return. You may wish to invoke CLEAR_OPT( SAVE_OPTS ) (see CLEAR_OPT( <NAME> ) - Clear Option Markings) beforehand if you do need to reinvoke optionProcess.

This option is activated by specifying one or more homerc attributes.

The method of saving the state may be altered by specifying flags before the output file name. “Flags” are specified by placing a list of them before the file name and separating them from the name with one or two greater-than characters (“>”). There are three flags currently supported:

‘default’

If an option has a default value (has not been set), then the default value is inserted as a comment.

‘usage’

Every option that can be processed from the configuration file will have a comment that contains the usage string that gets printed with the --help text

‘update’

Instead of removing the old file and writing a new one, the output file is kept, but any pre-existing segment labeled with <?program prog-name> is removed. The new program segment is placed at the end of the file. This flag is implied if the flags are separated from the file name with doubled greater-than characters. In other words, update,usage > file-name and usage >> file-name are identical.

‘reset-option -R’

This option takes the name of an option for the current program and resets its state such that it is set back to its original, compile-time initialized value. If the option state is subsequently stored (via --save-opts), the named option will not appear in that file.

This option is activated by specifying the resettable attribute.

BEWARE: If the resettable attribute is specified, all option callbacks must look for the OPTST_RESET bit in the fOptState field of the option descriptor. If set, the optCookie and optArg fields will be unchanged from their last setting. When the callback returns, these fields will be set to their original values. If you use this feature and you have allocated data hanging off of the cookie, you need to deallocate it.