Re: gobject

[Tristan Van Berkom <vantr touchtunes com>]

        I've been learning / coding widgets for about 6 months now
(And I'm very impressed by the do-it-yourself OOP style).

What I suggest is that you start from an exising object that inherits
from the same class as you inherit from and "modify / add / remove" from
that objects
functionality.

If I'm not mixed up with gtk specific stuff I think you 
need to specify the size of your instance in your "xxx_get_type()"
function and that you need your "static parent_class" to be the first
member
of your class. (its g_object_new that will use this information to
allocate space
for your object and build it). 

Have fun!
        -Tristan


Parrish M Myers wrote:
> Hello,
>
> I am not sure this is the right list to email... if not please forgive
> me.
>
> I am attempting to learn gobject (in glib2).  I have scoured the net
> looking for any tutorial I can find, and have come up empty.  I have
> studdied the API documentation for gobject... But, considering I don't
> understand what the basic elements look like the API documentation does
> me no good.  I am well versed with OO programming, I know java, C++,
> C#, bla bla bla...  But, for some reason I can't seem to grasp the
> syntacs of gobject.  Figuring, a good example bit of code should get
> the rest of the way, I have studdied libgsf, metacity, and gthumb, and
> have come up with what I think is a basic gobject class.
>
> Cany anyone comment on my code and tell me what I have done wrong or
> have not understood?  I would appreciate any constructive criticism...
> I am very willing to learn, I just need a little guidance from the
> masters :)
>
> #####################################################################
> /* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8
> -*- */
>
> /*
>  * timekeeper.h:
>  *
>  * Copyright (C) 2002 Parrish Myers (parrishmyers yahoo com)
>  *
>  * This program is free software; you can redistribute it and/or
>  * modify it under the terms of version 2 of the GNU General Public
>  * License as published by the Free Software Foundation.
>  *
>  * This program 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 General Public License for more details.
>  *
>  * You should have received a copy of the GNU General Public License
>  * along with this program; if not, write to the Free Software
>  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
>  * USA
>  */
>
> #ifndef TIMEPIECE_H
> #define TIMEPIECE_H
>
> #include <glib.h>
> #include <glib-object.h>
> #include "sw.h"
>
> G_BEGIN_DECLS
>
> #define SW_TIMEPIECE_TYPE  (sw_timepiece_get_type ())
> #define SW_TIMEPIECE(o)    (G_TYPE_CHECK_INSTANCE_CAST ((o),
> SW_TIMEPIECE_TYPE, SwTimepiece))
> #define SW_IS_TIMEPIECE(o) (G_TYPE_CHECK_INSTANCE_TYPE ((o),
> SW_TIMEPIECE_TYPE))
>
> typedef struct _SwTimepiece SwTimepiece;
>
> struct _SwTimepiece {
>         GObject g_object;
>         Timepiece_Mode mode;
>         Timepiece_Time time;
>
>         /* protected */
>         guint32 time_start;
>         guint32 time_now;
>
> };
>
> typedef struct {
>         GObjectClass g_object_class;
>
>         /*< signals >*/
>
>         void  (*Start_Error) (SwTimepiece *timepiece);
>
> } SwTimepieceClass;
>
> #define SW_TIMEPIECE_CLASS(k)    (G_TYPE_CHECK_CLASS_CAST ((k),
> SW_TIMEPIECE_TYPE, SwTimepieceClass))
> #define SW_IS_TIMEPIECE_CLASS(k) (G_TYPE_CHECK_CLASS_TYPE ((k),
> SW_TIMEPIECE_TYPE))
>
> GType        sw_timepiece_get_type (void);
> SwTimepiece *sw_timepiece_new      (void);
>
> /* protected */
> guint  sw_time_function  (SwTimepiece *timepiece);
> void   sw_set_mode       (SwTimepiece *timepiece, Timepiece_Mode
> *mode);
> void   sw_set_start_time (SwTimepiece *timepiece, Timepiece_Time
> *time);
> void   sw_start          (SwTimepiece *timepiece);
> void   sw_stop           (SwTimepiece *timepiece);
> void   sw_reset          (SwTimepiece *timepiece);
>
> G_END_DECLS
>
> #endif /* TIMEPIECE_H */
>
> /* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8
> -*- */
>
> /*
>  * timekeeper.c:
>  *
>  * Copyright (C) 2002 Parrish Myers (parrishmyers yahoo com)
>  *
>  * This program is free software; you can redistribute it and/or
>  * modify it under the terms of version 2 of the GNU General Public
>  * License as published by the Free Software Foundation.
>  *
>  * This program 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 General Public License for more details.
>  *
>  * You should have received a copy of the GNU General Public License
>  * along with this program; if not, write to the Free Software
>  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
>  * USA
>  */
>
> #include <glib.h>
> #include "sw.h"
> #include "timepiece.h"
>
> static guint start_error_signal;
>
> /* SwTimepiece */
>
> static void
> sw_timepiece_finalize (GObject *object)
> {
>         g_return_if_fail (object != NULL);
>         g_return_if_fail (SW_IS_TIMEPIECE (object));
>
>         G_OBJECT_CLASS (parent_class)->finalize (object);
> }
>
> static void
> sw_timepiece_class_init (SwTimepieceClass *class)
> {
>         GObjectClass *object_class = G_OBJECT_CLASS (class);
>
>         parent_class = g_type_class_peek_parent (class);
>
>         /* register signals */
>         start_error_signal = g_signal_new ("Start_Error",
>                                            G_TYPE_FROM_CLASS (class),
>                                            G_SIGNAL_RUN_LAST,
>                                            G_STRUCT_OFFSET (SwTimepieceClass, Start_Error),
>                                            NULL, NULL,
>                                            sw_marshal_VOID__VOID,
>                                            G_TYPE_NONE,
>                                            0);
>
>         object_class->finalize = sw_timepiece_finalize;
>
>         class->Start_Error = NULL;
> }
>
> static void
> sw_timepiece_init (SwTimepiece *timepiece)
> {
>         Timepiece_Time *time = {0, 0, 0};
>
>         timepiece->mode       = MODE_STOPWATCH;
>         timepiece->time       = time;
>         timepiece->time_start = sw_pack_time(time);
>         timepiece->time_now   = 0;
> }
>
> GType
> sw_timepiece_get_type ()
> {
>         static guint type = 0;
>
>         if (! type) {
>                 GTypeInfo type_info ={
>                         sizeof (SwTimepieceClass),
>                         NULL,
>                         NULL,
>                         (GClassInitFunc) sw_timepiece_class_init,
>                         NULL,
>                         NULL,
>                         sizeof (SwTimpiece),
>                         0,
>                         (GInstanceInitFunc) sw_timepiece_init
>                 };
>
>                 type = g_type_register_static (G_TYPE_OBJECT,
>                                                "SwTimepiece"
>                                                &type_info,
>                                                0);
>         }
>
>         return type;
> }
>
> SwTimepiece *
> sw_timepiece_new ()
> {
>         GObject *object;
>         object = g_object_new (SW_TIMEPIECE_TYPE, NULL);
>         return SW_TIMEPIECE (object);
> }
>
> guint
> sw_time_function (SwTimepiece *timepiece)
> {
> }
>
> void
> sw_set_mode (SwTimepiece *timepiece, Timepiece_Mode *mode)
> {
> }
>
> void
> sw_set_start_time (SwTimepiece *timepiece, Timepiece_Time *time)
> {
> }
>
> void
> sw_start (SwTimepiece *timepiece)
> {
> }
>
> void
> sw_stop (SwTimepiece *timepiece)
> {
> }
>
> void
> sw_reset (SwTimepiece *timepiece)
> {
> }
>
> guint32
> sw_pack_time (Timepiece_Time *time)
> {
>         guint32 packed_time = 0;
>
>         packed_time += time->hours   * 3600;
>         packed_time += time->minutes * 60;
>         packed_time += time->seconds;
>
>         return packed_time;
> }
>
> Timepiece_Time *
> sw_unpack_time (guint32 packed_time);
> {
>         Timepiece_Time *time = {0, 0, 0};
>
>         time->hours   = packed_time / 3600;
>         time->minutes = packed_time / 60 % 60;
>         time->seconds = packed_time % 60;
>
>         return time;
> }
>
> /* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8
> -*- */
>
> /*
>  * timekeeper.h:
>  *
>  * Copyright (C) 2002 Parrish Myers (parrishmyers yahoo com)
>  *
>  * This program is free software; you can redistribute it and/or
>  * modify it under the terms of version 2 of the GNU General Public
>  * License as published by the Free Software Foundation.
>  *
>  * This program 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 General Public License for more details.
>  *
>  * You should have received a copy of the GNU General Public License
>  * along with this program; if not, write to the Free Software
>  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
>  * USA
>  */
>
> #ifndef SW_H
> #define SW_H
>
> #include <glib.h>
> #include <glib-object.h>
>
> G_BEGIN_DECLS
>
> typedef struct {
>         gint hours;
>         gint minutes;
>         gint seconds;
> } Timepiece_Time;
>
> typedef enum {
>         MODE_STOPWATCH,
>         MODE_TIMER
> } Timepiece_Mode;
>
> guint32         sw_pack_time   (Timepiece_Time *time);
> Timepiece_Time *sw_unpack_time (guint32 time);
>
> G_END_DECLS
>
> #endif /* SW_H */
>
> =====
> -----------------------------------------------------------
> Academia is a little like child   | Parrish M. Myers
> rearing, it provides a chance at  | The Wacked Jester
> immortality without the stretch   | parrishmyers yahoo com
> marks  -- (unknown source)        |
> -----------------------------------------------------------
>
> __________________________________________________
> Do You Yahoo!?
> Yahoo! Autos - Get free new car price quotes
> http://autos.yahoo.com
> _______________________________________________
> gtk-app-devel-list mailing list
> gtk-app-devel-list gnome org
> http://mail.gnome.org/mailman/listinfo/gtk-app-devel-list