Re: what's the best way to handle variables and objects?

[Andreas Kotowicz <kotoml mynetix de>]

On Wed, 2006-03-15 at 13:44 -0500, John (J5) Palmieri wrote:
> You can create a generic struct but more often than not there is an
> application object or struct that the application developer creates
> which holds all the public variables he or she would care about which is
> passed as userdata to things like g_signal_connect.  

sorry, but I don't exactly understand what you mean. Could you maybe
give me an example of how the application object and the interaction
would look like? would this application object also hold all the labels
and entry fields which might change?

but maybe I do understand you. what I use here is following:

main.c:

#include <gtk/gtk.h>
#include "interface.h"
int main (int argc, char *argv[])
{

  GtkWidget *window1;

  gtk_init(&argc, &argv);

  window1 = create_window1 ();
  gtk_widget_show_all(window1);

  gtk_main();
  return 0;
}


interface.h:
#include <gtk/gtk.h>

GtkWidget* create_window1 (void);

interface.c:

#include "callbacks.h"
#include "interface.h"

GtkWidget*
create_window1 (void)
{
  GtkWidget *window;
  GtkWidget *vbox;
  GtkWidget *progressbar;
  GtkWidget *button_start;
  GtkWidget *spin_sec;
  GtkWidget *spin_min;

  window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
  gtk_window_set_title(GTK_WINDOW(window), "Window");
  g_signal_connect(G_OBJECT(window), "destroy", 
  G_CALLBACK(destroy_window_cb), NULL);
  
  /* vbox for whole window */
  vbox = gtk_vbox_new(FALSE, 6);
  gtk_container_add(GTK_CONTAINER(window), vbox);

  /* put progressbar at the top of the window */
  progressbar = gtk_progress_bar_new();
  gtk_box_pack_start(GTK_BOX(vbox), progressbar, TRUE, TRUE, 12);

  /* entry field for number of seconds */
  spin_sec = gtk_spin_button_new_with_range(0, 59, 1);  
  gtk_box_pack_start(GTK_BOX(vbox), spin_sec, FALSE, FALSE, 0);  

  
  button_start = gtk_button_new_with_mnemonic("_Start");
  gtk_box_pack_start(GTK_BOX(vbox), button_start, FALSE, FALSE, 0);

  g_signal_connect(GTK_BUTTON(button_start), "clicked", 
  G_CALLBACK(start_timer_cb), progressbar);
  
  return window;
}

is this what you mean by application object? here comes my problem now:
g_signal_connect on button_start only passes on the progressbar object
to start_timer_cb(). but I also want to have the user input from
spin_sec in this function. so how can I get a grip on both of these (or
even more) variables in start_timer_cb() ?

callbacks.c:

void start_timer_cb(GtkObject *window, void *data)
{
  GtkWidget *progressbar = data;
  gtk_progress_bar_set_fraction(GTK_PROGRESS_BAR(progressbar), 
  gtk_progress_bar_get_fraction(GTK_PROGRESS_BAR(progressbar))+0.1);
}


> BTW GtkObject is usually not used directly anymore.  Usually objects are
> passed to callbacks as GObject, GtkWidget or their actual class (in your
> case GtkButton) as they are the most useful casts. 

thanks, good to know. 


andreas