Polymorphism (computer science)
From Wiki @ Karl Jones dot com
In programming languages and type theory, polymorphism (from Greek πολύς, polys, "many, much" and μορφή, morphē, "form, shape") is the provision of a single interface to entities of different data types.
Description
A polymorphic type is one whose operations can also be applied to values of some other type, or types.
There are several fundamentally different kinds of polymorphism:
- Ad hoc polymorphism: when a function denotes different and potentially heterogeneous implementations depending on a limited range of individually specified types and combinations. Ad hoc polymorphism is supported in many languages using function overloading.
- Parametric polymorphism: when code is written without mention of any specific type and thus can be used transparently with any number of new types. In the object-oriented programming community, this is often known as generics or generic programming. In the functional programming community, this is often shortened to polymorphism.
- Subtyping (also called subtype polymorphism or inclusion polymorphism): when a name denotes instances of many different classes related by some common superclass. In the object-oriented programming community, this is often simply referred to as polymorphism.
The interaction between parametric polymorphism and subtyping leads to the concepts of variance and bounded quantification.
See also
- Ad hoc polymorphism
- Bounded quantification
- Covariance and contravariance (computer science)
- Data type
- Duck typing for polymorphism without (static) types
- Function overloading
- Object-oriented programming
- Parametric polymorphism
- Polymorphic code (Computer virus terminology)
- Subtyping
- System F for a lambda calculus with parametric polymorphism.
- Type class
- Type theory
- Virtual inheritance
External links
- Polymorphism (computer science) @ Wikipedia
