A note on before and after metamethods

Abstract

With the advent of object-oriented metalevel architectures, a new programming paradigm in the shape of before and after metamethods has arrived. This paradigm allows the hidden execution of additional functionality that previously had to be inserted explicitly into the source code of a program. Typically, this was implemented as a pair of invocations to some initialisation and finalisation routines. This paper provides the formal proof that before and after metamethods have the same expressive power as the explicit invocation of functionality, resulting in the equivalence of both paradigms.