Re: Pass more widgets as gpointer.

[Dov Grobgeld <dov grobgeld gmail com>]

As I've said in he past, I believe the best thing is to sub-class GtkWindow
and then make all the pointers you want to pass around members of your new
class. Conceptually this looks like:

    class MyWindow : GtkWindow {
            GtkWidget *w_label;
            GtkWidget *w_button;
            GtkWidget *w_tooltip;
    }

    :
    MyWindow *w_window = my_window_new();
    g_signal_connect(w_button, "clicked", G_CALLBACK(cb_button), w_window);
    :
    int cb_button(GtkWidget *widget,
                  GtkButtonEvent *event,
                  gpointer userdata)
       {
            MyWindow *self = (MyWindow*)self;

           gtk_tool_tip...(self->w_tooltip, ...);
           gtk_label_set_text(self->w_label, "foo");
       }


I hope you get the idea. The problem with this approach though is that it is
a bit of an effort quite to subclass Gtk in C, (in contrast to gtkmm, perl,
python, javascript in which it has been nicely mapped to the native objects,
not to talk about vala where a GObject is native). That's why I'm using gob2
whenever I'm writing C. It makes this technique as natural as in any other
language that I mentioned.

Regards,
Dov

2009/4/22 Vlad Volodin <vest 84 gmail com>

> Hi, Jens
>
> Yes, your way is good (thank you for a small code, maybe I will use it
> in my projects). But, are you sure your way is safe?
> You don't know the size of array (at the first),
> where do you free the array of pointers itself (try g_malloc and
> g_free, because it is GLIB :) ) (at the second).
> And I think, your way isn't type-safe (at the third), because you
> won't be sure that your element's type is needed.
> Well, of course I have many questions and now answers :) I think, in
> small projects your way is good (but you can also easily forget the
> order of the elements). Maybe HashTables, or STL sets will be more
> applicable.
>
> What do you think about all of this?
>
> Good luck in GTK programming :),
> Vlad Volodin
>
> 2009/4/22 Jens Hansen <jensh604 gmail com>:
> > Hi All.
> >
> > Thanks for all ideas, to this problem. I figured out how to pass more
> > widgets in an array, which is IMHO the best way to do it. Just for
> > reference, the following snippet.
> >
> > "Packing" the widgets pointers in the array
> >  GtkWidget * *data;
> >  data = malloc(sizeof(GtkWidget *)*3);
> >  data[0]=spinbutton;
> >  data[1]=combobox;
> >  data[2]=check_hidden
> > And "unpacking" them
> > GtkWidget * *array=(GtkWidget **)data;
> > Then you just need to type cast the elements of the array:
> > for instance
> >  gtk_combo_box_get_active((GtkComboBox *)array[1])
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