What's the essential difference between the two HandleException() methods of Exception Handling Application Block (Ent Lib 4.1)

Question

In the most recent version (4.1, released October 2008) of The Microsoft Enterprise Library's Exception Handling Application Block, there are two HandleException() method signatures, and I am a bit lost on the intent for these, especially since neither the documentation, intellisense, nor the QuickStart apps intimate any meaningful difference.

Here are the two signatures:

bool HandleException(Exception exceptionToHandle, string policyName);

bool HandleException(Exception exceptionToHandle, string policyName, out Exception exceptionToThrow);

All of the examples I have found use the first, as in this example straight out of the XML documentation comments on the actual method:

try
{
   Foo();
}
catch (Exception e)
{
   if (ExceptionPolicy.HandleException(e, name)) throw;
}

And here, from the same source (the XML doc comments for the method), is an example of using the second:

try
{
   Foo();
}
catch (Exception e)
{
   Exception exceptionToThrow;
   if (ExceptionPolicy.HandleException(e, name, out exceptionToThrow))
   {
      if(exceptionToThrow == null)
         throw;
      else
         throw exceptionToThrow;
   }
}

So, my question is, what does using the second one give you that the first does not? This should probably be obvious to me, but my head is a mess today and I don't really want to keep banging my head against the proverbial wall any longer. :)

No speculations, please; I hope to hear from someone that actually knows what they are talking about from experience using this.

Answer 1

If you use a replace handler in the enterprise library config, your replacement exception is returned by means of the second signature .. , out Exception exceptionToThrow).