gergelypolonkai-web-jekyll/content/blog/2013-01-06-registering-an-enum-type-in-glib-s-type-system.rst

Registering an enum type in GLib’s type system

date

2013-01-06T02:34:03Z

category

blog

tags

c,development,glib

url

blog/2013/1/6/registering-an-enum-type-in-glib-s-type-system.html

save_as

blog/2013/1/6/registering-an-enum-type-in-glib-s-type-system.html

status

published

author

Gergely Polonkai

I faced a problem in my GLib self-teaching project, wMUD today. I wanted to register a signal for a GObject, whose handler should accept two enum parameters for which I had to register a new GEnum type in the GObject type system. However, the documentation on this feature (thanks for pointing out goes to hashem on #gnome-hackers) is not… uhm… obvious. Making the long story short, I have checked with the GIO sources for an example, and using that, I have created this small, working chunk:

#ifndef __WMUD_CLIENT_STATE_H__
#define __WMUD_CLIENT_STATE_H__

#include <glib-object.h>

/**
 * WmudClientState:
 * @WMUD_CLIENT_STATE_FRESH: Client is newly connected. Waiting for a login
 *     player name
 * @WMUD_CLIENT_STATE_PASSWAIT: Login player name is entered, waiting for a
 *     login password
 * @WMUD_CLIENT_STATE_MENU: Authentication was successful, player is now in the
 *     main game menu
 * @WMUD_CLIENT_STATE_INGAME: Character login was successful, player is now
 *     in-game
 * @WMUD_CLIENT_STATE_YESNO: Player was asked a yes/no question, and we are
 *     waiting for the answer. client.yesNoCallback MUST be set at this point!
 *     TODO: if wmudClient had a prevState field, and there would be some hooks
 *     that are called before and after the client enters a new state, this
 *     could be a three-state stuff, in which the player can enter e.g ? as
 *     the answer, so they would be presented with the question again.
 * @WMUD_CLIENT_STATE_REGISTERING: Registering a new player. Waiting for the
 *     e-mail address to be given
 * @WMUD_CLIENT_STATE_REGEMAIL_CONFIRM: E-mail address entered séms valid,
 *     waiting for confirmation
 *
 * Game client states.
 */
typedef enum {
        WMUD_CLIENT_STATE_FRESH,
        WMUD_CLIENT_STATE_PASSWAIT,
        WMUD_CLIENT_STATE_MENU,
        WMUD_CLIENT_STATE_INGAME,
        WMUD_CLIENT_STATE_YESNO,
        WMUD_CLIENT_STATE_REGISTERING,
        WMUD_CLIENT_STATE_REGEMAIL_CONFIRM
} WmudClientState;


GType wmud_client_state_get_type (void) G_GNUC_CONST;
#define WMUD_TYPE_CLIENT_STATE (wmud_client_state_get_type())

#endif /* __WMUD_CLIENT_STATE_H__ */

#include "wmudclientstate.h"

GType
wmud_client_state_get_type (void)
{
        static volatile gsize g_define_type_id__volatile = 0;

        if (g_once_init_enter(&g_define_type_id__volatile)) {
                static const GEnumValue values[] = {
                        { WMUD_CLIENT_STATE_FRESH,            "WMUD_CLIENT_STATE_FRESH",            "fresh"            },
                        { WMUD_CLIENT_STATE_PASSWAIT,         "WMUD_CLIENT_STATE_PASSWAIT",         "passwait"         },
                        { WMUD_CLIENT_STATE_MENU,             "WMUD_CLIENT_STATE_MENU",             "menu"             },
                        { WMUD_CLIENT_STATE_INGAME,           "WMUD_CLIENT_STATE_INGAME",           "ingame"           },
                        { WMUD_CLIENT_STATE_YESNO,            "WMUD_CLIENT_STATE_YESNO",            "yesno"            },
                        { WMUD_CLIENT_STATE_REGISTERING,      "WMUD_CLIENT_STATE_REGISTERING",      "registering"      },
                        { WMUD_CLIENT_STATE_REGEMAIL_CONFIRM, "WMUD_CLIENT_STATE_REGEMAIL_CONFIRM", "regemail-confirm" },
                        { 0,                                  NULL,                                 NULL }
                };
                GType g_define_type_id = g_enum_register_static(g_intern_static_string("WmudClientState"), values);
                g_once_init_leave(&g_define_type_id__volatile, g_define_type_id);
        }

        return g_define_type_id__volatile;
}

Still, it can be made more perfect by using the glib-mkenums tool. I will read through the GLib Makefiles tomorrow for some hints on this.

Edit: you can find the glib-mkenums solution here.