Option parser

[Anders Carlsson <andersca gnome org>]

Hello,

I've been working on GOption, an option parser to be put in glib. In
GNOME we currently use popt which has problems that GOption tries to
adress:

* popt does not support utf-8 which results in things like the help
output not having the correct encoding under some circumstances.

* the popt API doesn't match the glib/gtk+ API very well.

* No good way to group options coming from different sources, for
example gtk options vs application options.

Option groups
-------------

In order to support options from different sources, GOption has
something called option groups. An option context has a main group, but
can also have a number of auxiliary groups for options coming from other
places. Options from other groups can also be merged into the main
group.

Here's the --help output from a simple app:

Usage:
  nautilus [OPTION...] [URI...]

Help Options:
  --help                    Show help options
  --help-all                Show all help options
  --help-gtk                Show Gtk+ help options

Application Options
  -b, --browser             Open a browser window
  -q, --quit                Quit Nautilus
  --no-desktop              Do not manage the desktop
  -d, --display=DISPLAY     X display to use

This app has a gtk group which has the --display option merged into the
main group. The --help-gtk output looks like this:

Usage:
  nautilus [OPTION...] [URI...]

Help Options:
  --help                    Show help options
  --help-all                Show all help options
  --help-gtk                Show Gtk+ help options

GTK+ Options
  -d, --display=DISPLAY     X display to use
  --g-fatal-warnings        Make all warnings fatal

This makes --help rather clean while still allowing the user to get
information about more rarely used options. (Try running nautilus --help
to see how it looks now, it's not pretty!)

I've modified gtk+ to use GOption for parsing and it seems to work, but
there's no new gtk+ API designed yet. (Perhaps a function like
gtk_init_with_goption_context would suffice, I'm not sure).

The API is attached, I welcome any comments or suggestions.

Anders

/* goption.h - Option parser
 *
 *  Copyright (C) 2004  Anders Carlsson <andersca gnome org>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

#ifndef __G_OPTION_H__
#define __G_OPTION_H__

#include <glib/gerror.h>
#include <glib/gquark.h>

G_BEGIN_DECLS

/* Should go into gtypes.h */
typedef const gchar * (*GTranslateFunc) (const gchar *str,
					 gpointer     data);

typedef struct _GOptionContext GOptionContext;
typedef struct _GOptionGroup   GOptionGroup;
typedef struct _GOptionEntry   GOptionEntry;

typedef enum
{
  G_OPTION_FLAG_HIDDEN       = 1 << 0,
  G_OPTION_FLAG_IN_MAIN      = 1 << 1,
} GOptionFlags;

typedef enum
{
  G_OPTION_ARG_NONE,
  G_OPTION_ARG_STRING,
  G_OPTION_ARG_INT,
  G_OPTION_ARG_CALLBACK,
  G_OPTION_ARG_FILENAME,
  G_OPTION_ARG_STRING_ARRAY,
  G_OPTION_ARG_FILENAME_ARRAY,
} GOptionArg;

typedef gboolean (*GOptionArgFunc) (const gchar    *option_name,
				    const gchar    *value,
				    gpointer        data,
				    GError        **error);

typedef gboolean (*GOptionParseFunc) (GOptionContext *context,
				      GOptionGroup   *group,
				      gpointer	      data,
				      GError        **error);

typedef void (*GOptionErrorFunc) (GOptionContext *context,
				  GOptionGroup   *group,
				  gpointer        data,
				  GError        **error);

#define G_OPTION_ERROR (g_option_context_error_quark ())

typedef enum
{
  G_OPTION_ERROR_UNKNOWN_OPTION,
  G_OPTION_ERROR_BAD_VALUE,
  G_OPTION_ERROR_FAILED
} GOptionError;

GQuark g_option_context_error_quark (void) G_GNUC_CONST;


struct _GOptionEntry
{
  const char *long_name;
  char        short_name;
  int         flags;

  GOptionArg  arg;
  gpointer    arg_data;
  
  const char *description;
  const char *arg_description;
};

GOptionContext *g_option_context_new              (const gchar         *parameter_string);
void            g_option_context_free             (GOptionContext      *context);
void		g_option_context_set_help_enabled (GOptionContext      *context,
						   gboolean		help_enabled);
gboolean	g_option_context_get_help_enabled (GOptionContext      *context);
void		g_option_context_set_ignore_unknown_options (GOptionContext *context,
							     gboolean	     ignore_unknown);
gboolean        g_option_context_get_ignore_unknown_options (GOptionContext *context);

void            g_option_context_add_main_entries (GOptionContext      *context,
						   const GOptionEntry  *entries,
						   const gchar         *translation_domain);
gboolean        g_option_context_parse            (GOptionContext      *context,
						   gint                *argc,
						   gchar             ***argv,
						   GError             **error);

void          g_option_context_add_group      (GOptionContext *context,
					       GOptionGroup   *group);
void          g_option_context_set_main_group (GOptionContext *context,
					       GOptionGroup   *group);
GOptionGroup *g_option_context_get_main_group (GOptionContext *context);


GOptionGroup *g_option_group_new                    (const gchar        *name,
						     const gchar        *description,
						     const char         *help_description,
						     gpointer            user_data,
						     GDestroyNotify      destroy);
void	      g_option_group_set_parse_hooks	    (GOptionGroup       *group,
						     GOptionParseFunc    pre_parse_func,
						     GOptionParseFunc	 post_parse_func,
						     gpointer		 data,
						     GDestroyNotify	 destroy_notify);
void	      g_option_group_set_error_hook	    (GOptionGroup       *group,
						     GOptionErrorFunc	 error_func,
						     gpointer		 data,
						     GDestroyNotify	 destroy_notify);
void          g_option_group_free                   (GOptionGroup       *group);
void          g_option_group_add_entries            (GOptionGroup       *group,
						     const GOptionEntry *entries);
void          g_option_group_set_translate_func     (GOptionGroup       *group,
						     GTranslateFunc      func,
						     gpointer            data,
						     GDestroyNotify      destroy_notify);
void          g_option_group_set_translation_domain (GOptionGroup       *group,
						     const gchar        *domain);





G_END_DECLS

#endif /* __G_OPTION_H__ */