Representing model classes in C

In object programming, the representation of model classes .— those explicit in the design domain — is a central concern. We develop a set of conventions for representing model classes in C++, and provide mechanisms which enforce the conventions. These mechanisms take the form of mixins which prohibit certain forms of bad behaviour. These conventions and support mechanisms are useful to any programmer, but are of particular help to the student, who may otherwise become lost among the many modes of expression offered by C++.