Question

I have this code:

using System;
using System.Runtime.Remoting.Messaging;

class Program {
    static void Main(string[] args) {
        new Program().Run();
        Console.ReadLine();
    }

    void Run() {
        Action example = new Action(threaded);
        IAsyncResult ia = example.BeginInvoke(new AsyncCallback(completed), null);
        // Option #1:
        /*
        ia.AsyncWaitHandle.WaitOne();
        try {
          example.EndInvoke(ia);
        }
        catch (Exception ex) {
          Console.WriteLine(ex.Message);
        }
        */
    }

    void threaded() {
        throw new ApplicationException("Kaboom");
    }

    void completed(IAsyncResult ar) {
        // Option #2:
        Action example = (ar as AsyncResult).AsyncDelegate as Action;
        try {
            example.EndInvoke(ar);
        }
        catch (Exception ex) {
            Console.WriteLine(ex.Message);
        }
    }
}

In many articles stands that when I call BeginInvoke, all Exceptions (here from method threaded) wait until I call EndInvoke and will be thrown there. But it doesn’t work, the Exception (“Kaboom”) is “unhandled” and the program crashes.
Can you help me?

Thanks!

Answer 1

That works fine. When you say “and the program crashes”, I’m wondering if you just have the IDE set to break on all exceptions. I get no crash with that – it writes “Kaboom” to the console, as we would expect. Try running it outside of the IDE or pressing ctrl+f5 instead of just f5.

I think you are just seeing the IDE being “helpful”:

Ignore that; the IDE doesn’t always get it right. That is still handled.