Question

I experienced on when refactoring some code, maybe I’m blind but I failed to see why the following code won’t work.

public bool Foo()
{
    try
    {
        return SomeFunctionMightThrow();
    }
    catch (Exception ex)
    {
        Logger.log(ex);
        throw ex;
    }
}

So far so good, if I refactor code to

public bool Foo()
{
  try
  {
    return SomeFunctionMightThrow();
  }
  catch (Exception ex)
  {
    LogAndThrow(ex);
  }
}

private void LogAndThrow(Exception ex)
{
  Logger.log(ex);
  throw ex;
}

Code does not compile now.

Answer 1

You could potentially change it to…

public bool Foo()
{
  try
  {
    return SomeFunctionMightThrow();
  }
  catch (Exception ex)
  {
    // note: this will reset the exception stack trace
    throw LogAndReturnException(ex);
  }
}

private Exception LogAndReturnException(Exception ex)
{
  Logger.log(ex);
  return ex;
}

This essentially does exactly what you want but gives VS the code return path.

Or for a more simplistic approach which will retain the stack trace, just change your catch to:

catch (Exception ex)
{
  Log(ex);
  throw; // retains stack trace
}