A NOTE ON BEFORE AND AFTER METAMETHODS

With the advent of object-oriented metalevel architectures, a new prog ramming paradigm in the shape of before and after metamethods has arri ved. This paradigm allows the hidden execution of additional functiona lity that previously had to be inserted explicitly into the source cod e of a program. Typically, this was implemented as a pair of invocatio ns to same initialisation and finalisation routines. This paper provid es the formal proof that before and after metamethods have the same ex pressive power as the explicit invocation of functionality, resulting in the equivalence of both paradigms.