.Net Exception peeking.(Update)

Question

Hi,

try  
{  
    throw new Exception("test");  
}  
finally  
{  
    //Inspect the exception ????  
    //Log(Exception);  
}

Is there a way to get the exception from the run-time in the finally?
I cannot use a catch :-)

Thanks for your answers.
I cannot use a catch because its not actually my code(to refactor).
We want to wrap a piece of code like that:

using(CriticalFlow(policy))  
{  
   //Not my code.  
   flow.Succeeded();  
}

In CriticalFlow finally block we need to inspect the exception, if succeeded was not called, and alert whoever by whichever means.
I hope it throws some light to the original question.

Thanks again.

Answer 1

When you reach the finally block the exception instance is already out of scope. The whole idea with try blocks is to have a place to inspect the exceptions. What you can do if you do not want to catch it is to simply rethrow it:

try
{
    // some exception is thrown
}
catch (Exception ex)
{
    // do some logging or so
    throw;
}

Answer 2

No, the exception is thrown up in the stack until it gets caught in a catch block.

Why are you not able to use catch ? :? You can catch the exception do wat you want to do with it, and re-throw it if you want.

Answer 3

I'm sorry but that is impossible...

Answer 4

No, you can't. If you can modify the rest of the code you could write:

Exception e = null;
try
{
    e = new Exception("test");
    throw e;
}
finally
{
    // Examine e
}

but you can't do anything "normally".

Could you wrap the whole thing in a logging method? Delegates could be helpful here, e.g.

LogExceptions(delegate
    {
        try
        {
            throw new Exception("test"0;
        }
        finally
        {
            // Not logged yet
        }
    }
);

Where LogExceptions would just try the specified action, catch any exceptions, log them and rethrow.

Answer 5

Exception helper;

try
{

}
catch (Exception ex)
{
    helper = ex;
}
finally
{
   if (helper != null)
   {
      process helper
   }
}

Answer 6

No, you cannot directly access exception object in finally block. What you can do, however, is to catch an exception in a catch block, store it in a local variable and then rethrow it using throw; statement.

Answer 7

why in finally ? finally will run whether an exception happaned or not, log exception in catch

Answer 8

This code can clarify our intention:

using (CriticalFlow cf = new CriticalFlow())
            {
                // code which can throws
                cf.Completed();
            }

public class CriticalFlow : IDisposable
    {
        private bool _completed = false;

        public void Completed()
        {
            this._completed = true;
        }

        #region IDisposable Members

        public void Dispose()
        {
            if (this._completed == false)
            {
               // can i peek the exception at this point?
            }
        }

        #endregion
    }