Implementing Statically Typed Object-Oriented Programming Languages

Аннотация

Object-oriented programming represents an original implementation issue due to its philosophy of making the program behavior depend on the dynamic type of objects. This is expressed by the late binding mechanism, aka message sending. The underlying principle is that the address of the actually called procedure is not statically determined at compile-time, but depends on the dynamic type of a distinguished parameter known as the receiver. A similar issue arises with attributes, because their position in the object layout may also depend on the object's dynamic type. Furthermore, subtjrping introduces another original feature (i.e., runtime subtype checks). All three mechanisms need specific implementations and data structures. In static typing, late binding is generally implemented with so-called virtual function tables. These tables reduci! method calls to pointers to functions via a small fixed number of extra indirections. It follows that objectoriented programming yields some overhead, as compared to the usual procedural languages.