[aspectj-users] Need help refactoring an input validation aspect

[David Coppit <aspectj@xxxxxxxxxx>]

Hello everyone,

I'm just getting started with AspectJ, and have gotten stuck on extracting
some exception handling concerns. Can anyone point me in the right
direction?

Here's the original code:

  private static int promptForNumber(final BufferedReader stdin) {
    int inputSize = 0;

    boolean inputIsValid = false;
    while (!inputIsValid) {
      try {
        inputSize = Integer.parseInt(stdin.readLine());

        inputIsValid = true;
      } catch (IOException e) {
        System.err.println(
          "Encountered an I/O exception. Exiting.");
        System.exit(1);
      } catch (NumberFormatException e) {
        System.err.println(
          "Invalid number entered. (" + e.getMessage() + ")" );
      }
    }

    return inputSize;
  }

I extracted an IOException handling aspect, as follows:

  aspect IOExceptionHandling {
    declare soft : IOException
        : call(* *.*(..) throws IOException) &&
          within(Average);

    after() throwing(org.aspectj.lang.SoftException e)
        : execution(* Average.*(..)) && within(Average) {
      if (e.getWrappedThrowable() instanceof IOException) {
        System.err.println(
          "Encountered an I/O exception. Exiting.");
        System.exit(1);
      }
    }
  }

Now I'd like to extract the NumberFormatException handler, and (ideally)
the inputIsValid and while loop.

At the end, I was hoping to have something like:

  aspect IOExceptionHandling {
    ...
  }

  aspect InputValidation {
    ...
  }

  private static int promptForNumber(final BufferedReader stdin) {
    return Integer.parseInt(stdin.readLine());
  }

I might be asking for a lot, especially with the looping, but any help
would be appreciated. :)

Thanks,
David

_____________________________________________________________________
Dr. David Coppit                    Assistant Professor
coppit@xxxxxxxxx                    Department of Computer Science
http://www.cs.wm.edu/~coppit/       The College of William and Mary