public void Add(int x)
{
total += x;
if (total >= threshold)
{
ThresholdReachedEventArgs args = new ThresholdReachedEventArgs();
args.Threshold = threshold;
args.TimeReached = DateTime.Now;
OnThresholdReached(args);
}
}
//Call the delegate ThresholdReached (created below) when called above in the Add function (which calls this when the private field total gets to be
//greater than the int value that was passed into this class in the consructor.
protected virtual void OnThresholdReached(ThresholdReachedEventArgs e)
{
/*Thread Safety - Copy the event delegate (creating a multicast Delegate) to a temporary local variable before raising it to avoid the following issue:
* Assume we have thread A which is about to raise the event, and it checks and clears the null check and is about to raise the event.
* However, before it can do that thread B unsubscribes to the event, which sets the delegate to null. Now, when thread A attempts to raise the event,
* this causes the NullReferenceException that we were hoping to avoid!
*/
//Syntax to use when fomrally declaring the event delegate below
//ThresholdReachedEventHandler handler = ThresholdReached;
//Syntax to use when not formally declaring the event delegate type but using the shortcut instead
EventHandler <ThresholdReachedEventArgs> handler = ThresholdReached;
if (handler != null)
{
handler(this, e);
}
}
static void c_ThresholdReached(object sender, ThresholdReachedEventArgs e)
{
Console.WriteLine("The threshold of {0} was reached at {1}.", e.Threshold, e.TimeReached);
Console.ReadLine();
Environment.Exit(0);
}
