gergelypolonkai-web-jekyll/_posts/2013-01-06-registering-an-enum-type-in-glib-s-type-system.markdown

layout	title	date	tags	permalink	published	author
post	Registering an enum type in GLib’s type system	2013-01-06 02:34:03+00:00	c development glib	/blog/2013/1/6/registering-an-enum-type-in-glib-s-type-system	true	name email Gergely Polonkai gergely@polonkai.eu

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:

{% highlight c %} #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 */ {% endhighlight %}

{% highlight c %} #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;

} {% endhighlight %}

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.