Question

Let us say we have an external server which we use (e.g.-telephony station, etc.). Also we have the next code:

try
{
   externalService.CreateCall(callParams);
}
catch (Exception ex)
{
   _log.Error("Unexpected exception when trying execute an external code.", ex);
   _callService.UpdateCallState(call, CallState.Disconnected, CallOutcome.Failed);
   throw;
}

Theoretically UpdateCallState could throw but we would hide this exception using that code and would treat only exceptions generated by CreateCall in a right way.

The question is, what is the right pattern for these situations so that we treat all the exceptions correctly?

Answer 1

You can always nest another try..catch inside the first catch and deal with it appropriately.

try
{
   externalService.CreateCall(callParams);
}
catch (Exception ex)
{
   _log.Error("Unexpected exception when trying execute an external code.", ex);
   try
   {
       _callService.UpdateCallState(call, CallState.Disconnected, CallOutcome.Failed);
   }
   catch(Exception updateEx)
   {
       // do something here, don't just swallow the exception
   }
   throw; // this still rethrows the original exception
}