static void Main()
{
Observable subject = new Observable();
Observer watcher = new Observer();
Console.WriteLine("subscribe new WeakEventHandler()\n");
subject.OnChange += new WeakEventHandler(watcher.OnChange);
subject.Change();
Console.WriteLine("\nObserver = null, GC");
watcher = null;
GC.Collect(0, GCCollectionMode.Forced);
GC.WaitForPendingFinalizers();
subject.Change();
if (Debugger.IsAttached)
{
Console.Write("Press any key to continue . . . ");
Console.ReadKey(true);
}
}