The theory of classification part 17: multiple inheritance and the resolution of inheritance conflicts

The author considers the theoretical issues raised by combining multiple implementations. Then, he considers what it means for an object to belong to multiple parent classes, defining the notion of multiple classification

The theory of classification part 20: modular checking of classtypes

A first-order type system has two things to commend it. Firstly, it is quite simple to implement a type-checker that can check types for exact correspondence, or for subtype compatibility with a given type. The type of the source object can be compared with that of the target variable to see if the former can be converted up to the latter, using subtyping rules like those we discussed in [1]. Secondly, code that has been checked once need never be checked again, or recompiled in new contexts. This is because the type system can never reveal more specific information about an object that is passed into a more general variable (which we have called the “type loss problem”), so the code need only be checked once over the most general type that it can accept

The theory of classification, Part 17: Multiple inheritance and the resolution of inheritance conflicts

This is the seventeenth article in a regular series on object-oriented theory for nonspecialists. Using a second-order λ-calculus model, we have previously modelled the notion of inheritance as a short-hand mechanism for defining subclasses by extending superclass definitions. Initially, we considered the inheritance of type [1] an