OptionArg

The OptionArg enum values determine which type of extra argument the options expect to find.

If an option expects an extra argument, it can be specified in several ways; with a short option: `-x arg`, with a long option: `--name arg` or combined in a single argument: `--name=arg`.

Example: Commandline parsing:

public class Main : Object {
	private static bool version = false;
	private static string? directory = null;
	[CCode (array_length = false, array_null_terminated = true)]
	private static string[]? importdirs = null;
	private static string? driver = null;
	[CCode (array_length = false, array_null_terminated = true)]
	private static string[]? import_packages = null;
	private static double numd = 0;
	private static int64 numi64 = 0;
	private static int numi = 0;

	private const GLib.OptionEntry[] options = {
		// --version
		{ "version", '\0', OptionFlags.NONE, OptionArg.NONE, ref version, "Display version number", null },

		// --directory FIlENAME || -o FILENAME
		{ "directory", 'o', OptionFlags.NONE, OptionArg.FILENAME, ref directory, "Output directory", "DIRECTORY" },
		// [--vapidir FILENAME]*
		{ "importdir", '\0', OptionFlags.NONE, OptionArg.FILENAME_ARRAY, ref importdirs, "Look for external documentation in DIRECTORY", "DIRECTORY..." },

		// --driver
		{ "driver", '\0', OptionFlags.NONE, OptionArg.STRING, ref driver, "Use the given driver", "DRIVER" },
		// [--import STRING]*
		{ "import", '\0', OptionFlags.NONE, OptionArg.STRING_ARRAY, ref import_packages, "Include binding for PACKAGE", "PACKAGE..." },

		// --double DOUBLE
		{ "double", '\0', OptionFlags.NONE, OptionArg.DOUBLE, ref numd, "double value", "DOUBLE" },
		// --int64 INT64
		{ "int64", '\0', OptionFlags.NONE, OptionArg.INT64, ref numi64, "int64 value", "INT64" },
		// --int INT
		{ "int", '\0', OptionFlags.NONE, OptionArg.INT, ref numi, "int value", "INT" },

		// list terminator
		{ null }
	};

	public static int main (string[] args) {
		try {
			var opt_context = new OptionContext ("- OptionContext example");
			opt_context.set_help_enabled (true);
			opt_context.add_main_entries (options, null);
			opt_context.parse (ref args);
		} catch (OptionError e) {
			printerr ("error: %s\n", e.message);
			printerr ("Run '%s --help' to see a full list of available command line options.\n", args[0]);
			return 1;
		}

		if (version) {
			print ("Test 0.1\n");
			return 0;
		}


		print ("Paths:\n");
		print (@" directory: '$directory'\n");
		print (" importdir: ");
		foreach (string str in importdirs) {
			print (@"'$str' ");
		}
		print ("\n\n");


		print ("Strings:\n");
		print (@" driver: '$driver'\n");
		print (" import: ");
		foreach (string str in import_packages) {
			print (@"'$str' ");
		}
		print ("\n\n");


		print ("Numeric:\n");
		print (@" double:  $numd\n");
		print (" int64:   %" + int64.FORMAT + "\n", numi64);
		print (@" int:     $numi\n");
		print (@" version: $version\n");

		// Help:
		//  ``Usage:``
		//  ``	test2 [OPTION...] - OptionContext example``
		//  ``
		//  ``	Help Options:``
		//  ``	  -h, --help                    Show help options``
		//  ``
		//  ``	Application Options:``
		//  ``	  --version                     Display version number``
		//  ``	  -o, --directory=DIRECTORY     Output directory``
		//  ``	  --importdir=DIRECTORY...      Look for external documentation in DIRECTORY``
		//  ``	  --driver=DRIVER               Use the given driver``
		//  ``	  --import=PACKAGE...           Include binding for PACKAGE``
		//  ``	  --double=DOUBLE               double value``
		//  ``	  --int64=INT64                 int64 value``
		//  ``	  --int=INT                     int value``

		return 0;
	}
}

valac --pkg glib-2.0 GLib.OptionContext.vala