100 lines
4.0 KiB
Markdown
100 lines
4.0 KiB
Markdown
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---
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layout: post
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title: "Registering an enum type in GLib’s type system"
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date: 2013-01-06 02:34:03+00:00
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tags: [c, development, glib]
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permalink: /blog/2013/1/6/registering-an-enum-type-in-glib-s-type-system
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published: true
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author:
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name: Gergely Polonkai
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email: gergely@polonkai.eu
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---
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I faced a problem in my [GLib](https://developer.gnome.org/glib/) self-teaching
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project, [wMUD](https://github.com/gergelypolonkai/wmud) today. I wanted to
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register a signal for a `GObject`, whose handler should accept two `enum`
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parameters for which I had to register a new `GEnum` type in the `GObject` type
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system. However, the [documentation on this
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feature](https://developer.gnome.org/gobject/unstable/gtype-non-instantiable.html)
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(thanks for pointing out goes to hashem on `#gnome-hackers`) is not… uhm…
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obvious. Making the long story short, I have checked with the `GIO` sources for
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an example, and using that, I have created this small, working chunk:
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{% highlight c %}
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#ifndef __WMUD_CLIENT_STATE_H__
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#define __WMUD_CLIENT_STATE_H__
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#include <glib-object.h>
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/**
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* WmudClientState:
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* @WMUD_CLIENT_STATE_FRESH: Client is newly connected. Waiting for a login
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* player name
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* @WMUD_CLIENT_STATE_PASSWAIT: Login player name is entered, waiting for a
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* login password
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* @WMUD_CLIENT_STATE_MENU: Authentication was successful, player is now in the
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* main game menu
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* @WMUD_CLIENT_STATE_INGAME: Character login was successful, player is now
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* in-game
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* @WMUD_CLIENT_STATE_YESNO: Player was asked a yes/no question, and we are
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* waiting for the answer. client.yesNoCallback MUST be set at this point!
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* TODO: if wmudClient had a prevState field, and there would be some hooks
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* that are called before and after the client enters a new state, this
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* could be a three-state stuff, in which the player can enter e.g ? as
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* the answer, so they would be presented with the question again.
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* @WMUD_CLIENT_STATE_REGISTERING: Registering a new player. Waiting for the
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* e-mail address to be given
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* @WMUD_CLIENT_STATE_REGEMAIL_CONFIRM: E-mail address entered séms valid,
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* waiting for confirmation
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*
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* Game client states.
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*/
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typedef enum {
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WMUD_CLIENT_STATE_FRESH,
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WMUD_CLIENT_STATE_PASSWAIT,
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WMUD_CLIENT_STATE_MENU,
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WMUD_CLIENT_STATE_INGAME,
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WMUD_CLIENT_STATE_YESNO,
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WMUD_CLIENT_STATE_REGISTERING,
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WMUD_CLIENT_STATE_REGEMAIL_CONFIRM
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} WmudClientState;
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GType wmud_client_state_get_type (void) G_GNUC_CONST;
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#define WMUD_TYPE_CLIENT_STATE (wmud_client_state_get_type())
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#endif /* __WMUD_CLIENT_STATE_H__ */
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{% endhighlight %}
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{% highlight c %}
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#include "wmudclientstate.h"
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GType
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wmud_client_state_get_type (void)
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{
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static volatile gsize g_define_type_id__volatile = 0;
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if (g_once_init_enter(&g_define_type_id__volatile)) {
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static const GEnumValue values[] = {
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{ WMUD_CLIENT_STATE_FRESH, "WMUD_CLIENT_STATE_FRESH", "fresh" },
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{ WMUD_CLIENT_STATE_PASSWAIT, "WMUD_CLIENT_STATE_PASSWAIT", "passwait" },
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{ WMUD_CLIENT_STATE_MENU, "WMUD_CLIENT_STATE_MENU", "menu" },
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{ WMUD_CLIENT_STATE_INGAME, "WMUD_CLIENT_STATE_INGAME", "ingame" },
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{ WMUD_CLIENT_STATE_YESNO, "WMUD_CLIENT_STATE_YESNO", "yesno" },
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{ WMUD_CLIENT_STATE_REGISTERING, "WMUD_CLIENT_STATE_REGISTERING", "registering" },
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{ WMUD_CLIENT_STATE_REGEMAIL_CONFIRM, "WMUD_CLIENT_STATE_REGEMAIL_CONFIRM", "regemail-confirm" },
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{ 0, NULL, NULL }
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};
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GType g_define_type_id = g_enum_register_static(g_intern_static_string("WmudClientState"), values);
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g_once_init_leave(&g_define_type_id__volatile, g_define_type_id);
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}
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return g_define_type_id__volatile;
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}
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{% endhighlight %}
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Still, it can be made more perfect by using the
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[glib-mkenums](http://developer.gnome.org/gobject/stable/glib-mkenums.html)
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tool. I will read through the GLib Makefiles tomorrow for some hints on
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this.
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