To date, much of the software written in Computational Physics has been produced with little regard paid to modern software engineering techniques; this paper documents experiences in beginning to address this shortcoming for Config, a component of the Graphical R-Matrix Atomic Collision Environment (GRACE). The work is based around a formal specification of the Config component. The principal focus of the paper will be on a non-intrusive mechanism for monitoring constraints such as class invariants, preconditions and postconditions for highly structured data types based on the containers and algorithms of the Standard Template Library (STL), a mechanism which can be extended to handle structured object update and display prototyping.