3.2. Add a Button with a Callback

#!/usr/cogent/bin/gamma

/* Example: Button-controlled "Hello world!"
 * This example creates a button in a window that calls
 * a "Hello, world!" function and then quits GTK,
 * demonstrating the use of callbacks.
 */

/* Initialize Cogent interprocess communication, which is
 * necessary for using Gamma/GTK.
 */
init_ipc("a", "aq");

/* Write a Hello, world! function. */
function hello()
{
  princ("Hello, world!\n");
}


/* Create a GtkWindow and a GtkButton. */
window = new(GtkWindow);
window.set_border_width(20);
button = new(GtkButton);
button.label = " Click me! ";


/* Add callbacks to the button to execute the
 * "Hello, world!" function and quit.
 */
button.signal("clicked",#hello());
button.signal("clicked",#gtk_main_quit());


/* Add the button to the window, and show them both.*/
window.add(button);
window.show_all();


/* Enter the GTK main processing loop.*/
gtk_main();