I think that mmjoy, which you point out, or FreeJoy, which I just saw here on the forum, are good evidence that this general approach is well established. They both seem good for big projects where you might have a lot of controls to keep straight. Once you wanted more than a couple of controls, my approach would start becoming a PITA and using these frameworks would be better. More importantly, you should not have to maintain code. Most signal transformations won't need unexpected code.