Re: strange gtk_set_data_full behavior ...

[Sven LUTHER <luther maxime u-strasbg fr>]

On Wed, Jun 09, 1999 at 07:51:42AM -0400, Owen Taylor wrote:
> > > The warning is indicating that you can't set a destroy function
> > > for a NULL data pointer. (The reason for this is that
> > > gtk_object_set_data (object, key, NULL) actually removes
> > > that key from the list attached to the widget.
> > 
> > Why not just ignore the function then, and remove the data ? Why give an error
> > for that ?
> 
> I think the reason that there is a warning there is so that
> people won't expect the destroy function to be called if
> that key is subsequently set again. Ignoring that argument

huh ?

if you reset the key, you have to provide a new destroy function, isn't it ? Or do
you mean that the people expect the destroy function to be called with the NULL
argument then ...

> > PS : is this kind of mail correct for this list, or should it go to
> > gtk-list ?  I am not sure where to address my mails. I am writting a
> > binding for the ocaml language, not an application.
> 
> This mail would be more appropriate on gtk-list, since it
> doesn't really deal with development plans for future versions
> of GTK+.

Ok, i will no more post here then, 

> #include <gtk/gtk.h>
> #include <stdio.h>
> 
>  char data1[] = "Hello";
>  char data2[] = "Bye";
>  char data3[] = "XXX";
>  
> 
> void sven_free (gpointer data)
>  {
>    printf ("Hello you %u.\n", data);
>    printf ("Data is %s.\n", data);
>  }
> 
> int main (int argc, char **argv)
> {
>   GtkWidget *window;
> 
>   gtk_init (&argc, &argv);
> 
>   window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
>  
>   printf ("Data1 = %u.\n", data1);
>   printf ("Data2 = %u.\n", data2);
>   printf ("Data3 = %u.\n", data3);
>   gtk_object_set_data_full (GTK_OBJECT (window), "Sven_data",\
> 			    (gpointer)data1, (GtkDestroyNotify)&sven_free);
>   gtk_object_set_data_full (GTK_OBJECT (window), "Sven_data",\
> 			    (gpointer)data2, (GtkDestroyNotify)&sven_free);
>   gtk_object_set_data_full (GTK_OBJECT (window), "Sven_data",\
> 			    (gpointer)data3, (GtkDestroyNotify)&sven_free);
>   gtk_object_set_data_full (GTK_OBJECT (window), "Sven_data",\
> 			    (gpointer)NULL, (GtkDestroyNotify)&sven_free);
> 
>   gtk_widget_show (window);
> 
>   gtk_widget_destroy (window);
> }

So the main difference is that the button press callback calls  gtk_exit (0);
in my example.

I suppose gtk_exit exits without doing any cleanup after himself, while
gtk_widget_destroy kills the widget cleanly ...

Friendly,

Sven LUTHER