Open AccessSubstitution Polymorphism for Object-Oriented Programming
Author(s) -
Jens Palsberg,
Michael I. Schwartzbach
Publication year - 1990
Publication title -
daimi pb
Language(s) - English
Resource type - Journals
eISSN - 2245-9316
pISSN - 0105-8517
DOI - 10.7146/dpb.v19i305.6698
Subject(s) - programming language , substitution (logic) , eiffel , computer science , object oriented programming , class (philosophy) , reuse , code reuse , theoretical computer science , artificial intelligence , software , biology , ecology
We introduce substitution polymorphism as a new basis for typed object-oriented languages. While avoiding subtypes and polymorphic types, this mechanism enables optimal static type-checking of generic classes and polymorphic functions. The novel idea is to view a class as having a family of implicit subclasses, each of which is obtained through a substitution of types. This allows instantiation of a generic class to be merely subclassing and resolves the problems in the Eiffel type system reported by Cook. All subclasses, including the implicit ones, can reuse the code implementing their superclass.