Can I overload the throw keyword?

Question

I want to overload the throw keyword to catch a class which inherits from Exception and to have it do some logging and other stuff before the actual throw. Is this possible? Or do I have to use a regular function?

I've tried:

public class cSilException : Exception
    {
        private string m_strMsg;

        public override void throw(cSilException ex)
        {

        }
...
...
}

Answer 1

Register the event AppDomain.FirstChanceException. There you get all exceptions before the are actually thrown. In the event handler you can check for your exception and do the required logging.

No magic and no bad design.

class Program
{
    static void Main(string[] args)
    {
        AppDomain.CurrentDomain.FirstChanceException += CurrentDomain_FirstChanceException;
        DoBadThings();
    }

    private static void DoBadThings()
    {
        DoOneLevelBelow();
    }

    private static void DoOneLevelBelow()
    {

        for(int i=0;i<10;i++)
        {
            try
            {
                if (i == 5)
                {
                    var invalidCast = (string)((object)i);
                }
                else
                {
                    throw new InvalidTimeZoneException();
                }
            }
            catch
            {

            }
        }
    }

    static void CurrentDomain_FirstChanceException(object sender, System.Runtime.ExceptionServices.FirstChanceExceptionEventArgs e)
    {
        if( e.Exception is InvalidCastException)
        {
            LogInvalidCast((InvalidCastException)e.Exception);
        }
    }

    private static void LogInvalidCast(InvalidCastException invalidCastException)
    {
        Console.WriteLine("Got Invalid cast: {0}", invalidCastException);
    }

This will lead to:

Got invalid cast: System.InvalidCastException: The object of the type "System.Int32" cannot be converted to "System.String". at ThrowTest.Program.DoOneLevelBelow() in d:\Media\Blog\ThrowTest\Program.cs:line 31.

Please note since you are getting the exception before the stack is unwound you will see only the method where it did happen but not the calling methods since the stack was not unwound yet. If you want the complete call stack you can use Environment.StackTrace to get all stack frames.