Re: how to access a widget ?

[edward hage <edha xs4all nl>]

I cracked the problem, was an matter of allocating space. Also not assigning &buttonreeks 
but buttonreeks.
Also one pointer and changing the value for every button was not good, in hindside very 
obvious because every button needs a different pointer otherwise every button will do the 
same (pointing to the same data). So I made an array of pointers.

That leaves me only with two questions:
1) Can this be achieved more simple ?
2) I declared "struct _buttonreeks *buttonreeks[30]; " because this is in most cases large 
enough, but how can I make it lenght-independant (what if I need 32 ??).
struct _buttonreeks *buttonreeks[] does not compile !!

for those who are interested the solution given below:

struct _buttonreeks *buttonreeks[30];
GtkWidget *button;
struct table_description foo;
GArray *buts = NULL;

buts = g_array_sized_new (FALSE, FALSE, sizeof (struct table_description), 1);

...etc...

for (i=0; i < vertical - 1; i++)
{
   .... other things .

  for (j=1; j < vertical; j++)
  {
   if ((i < j) && Link_exists(i,j))
   {
     button = gtk_button_new ();
     gtk_button_set_label ((GtkButton *) button , " x");
     gtk_table_attach_defaults (GTK_TABLE (table), button , 1 + j, 2 + j, 1 + i, 2 + i);
	
    foo.buttons = button;  // get the information and store it in the GArray
    foo.i = i;
    foo.j = j;
    g_array_append_vals (buts, &foo, 1);
    }
   }
}

// g_signal_connect for all buttons
for (i=0; i < buts->len; i++)
{
  buttonreeks[i] = (struct _buttonreeks *) g_malloc(sizeof(struct _buttonreeks));
  buttonreeks[i]->buttonids = buts;
  buttonreeks[i]->i = g_array_index (buts, struct table_description, i).i;
  buttonreeks[i]->j = g_array_index (buts, struct table_description, i).j;
  button = g_array_index (buts, struct table_description, i).buttons;
  g_signal_connect (G_OBJECT(button), "clicked",
                      (GCallback) toggle_location_event, buttonreeks[i]);
}


edward hage wrote:
> Tiago Cogumbreiro wrote:
>
> > You can cache a matrix with your buttons and the last changed buttons in
> > a structure[1] and then send this structure[2] as user data (in the
> > callback).
> ...........
>
> Thank you for the advice,
> Got that, I made the following structures. Looks much like you proposed, 
> only use GArray to fill it with buttons and location (i,j) info.
>
> struct _buttonreeks
> {
>   GArray *buttonids;
>   guint i;
>   guint j;
> };
>
> struct table_description
> {
>   GtkButton *buttons;
>   guint i;
>   guint j;
> };
>
> I get the following error-message when I run the program (compiling and
> linking all okay!)
>
> edward linux:~/Projects/modeller> ./modeller9
>
> (modeller9:8722): GLib-GObject-WARNING **: invalid (NULL) pointer instance
>
> (modeller9:8722): GLib-GObject-CRITICAL **: file gsignal.c: line 1861 
> (g_signal_connect_data): assertion `G_TYPE_CHECK_INSTANCE (instance)' 
> failed
> Segmentatie fout
> edward linux:~/Projects/modeller>
>
> How can I solve this problem ?