Question

Basically, what I want to do is pass a specific Exception to a more general Exception within the same try block. I’ve tried the following and it doesn’t work:

    static bool example(int count = 0)
    {
        try
        {
            work();
        }
        catch (TimeoutException e)
        {
            if (count < 3)
            {
                Console.WriteLine("Caught TimeoutException: {0}", e.Message);
                return example(count + 1);
            }
            else
            {
                throw new Exception(e.Message);
            }
        }
        catch (Exception e)
        {
            Console.WriteLine("Caught Exception: {0}", e.Message + " rethrown");
            return false;
        }
        return true;
    }

    static void work()
    {
        throw new TimeoutException("test");
    }

I want the TimeoutException to be only handled a certain amount of times before going to a more generic Exception. This is because the TimeoutException has additional information about the exception on a case by case basis. I do not want to duplicate the code for Exception under the else clause of TimeoutException. The reason I want all exceptions to be handled is that there may be other unknown exceptions that are thrown. The nature of the program requires it to not crash so I must account for any other exceptions and log them. How can I implement this?

Answer 1

Here’s my take:

bool example()
{
    // Attempt the operation a maximum of three times.
    for (int i = 0; i < 3; i++)
    {
        try
        {
            work();
            return true;
        }
        catch (Exception e)
        {
            Console.WriteLine("Caught exception {0}", e.Message);

            // Fail immediately if this isn't a TimeoutException.
            if (!(e is TimeoutException))
                return false;
        }
    }

    return false;
}

EDIT

If you want to actually do something with the TimeoutException, you could change the catch block like so:

catch (Exception e)
{
    // As Reed pointed out, you can move this into the if block if you want
    // different messages for the two cases.
    Console.WriteLine("Caught exception {0}", e.Message);

    TimeoutException timeoutException = e as TimeoutException;
    if (timeoutException != null)
    {
        // Do stuff with timeout info...
    }
    else
    {
        // Not a timeout error, fail immediately
        return false;
    }
}