On 22-12-2018 13:34, Ron Tarrant wrote:

I've run into something that has me scratching my head. The following code, based on a number of similar examples, doesn't work. I'm starting to think I can only hook an event to a button if it's subclassed.

Can anyone set me straight?

......

The main issue is that the quitApp function is a static function so
taking it's address will return a function pointer and not a delegate.

There are a few ways to go about fixing that:

• use std.functional.toDelegate to turn it into a delegate.
• Put the function inside main as a nested function, it will be a
  delegate in that case.
• Wrap the call in a anonymous delegate as with addOnDestroy.
• Use gobject.Signals.connect which also accepts function pointers.

There were two smaller issues with the example:

• The return type of quitApp should be bool.
• Missing std.stdio import.

import gtk.MainWindow;
import gtk.Main;
import gtk.Button;
import gtk.Widget;
import gdk.Event;

import std.stdio;
import std.functional;

void main(string[] args)
{
	Main.init(args);
	MainWindow myAppWin = new MainWindow("Test Rig");

	Button myButt = new Button();
	myButt.setLabel("My Butt");
	
	myButt.addOnButtonRelease(toDelegate(&quitApp));
	
	myAppWin.add(myButt);
	
	myAppWin.addOnDestroy(delegate void(Widget w) { quitApp(null, null); });
	myAppWin.showAll();
	Main.run();
	
} // main()

bool quitApp(Event event, Widget widget)
{
	writeln("Quit, eh");
	
	Main.quit();
	
	return(true);
} // quitApp()