Setting attributes/resources through qalter or qmgr is an atomic operation. If any set operation fails, we won't set anything. Value validity is handled through special a function associated with the attribute called an action function. If one of these action functions sets something on an object (e.g., set something in the object's quick save area), this will not be undone if the atomic operation fails.
Action functions are called with a mode. This mode is set to what type of action which is being performed (new, alter, etc). I suggest we add another mode which will be called post-alter. This means all of the action functions have been called and passed. The atomic operation has been successful. The function can handle this new mode to set anything outside of the normal value of the attribute itself.