Terminology on generics types

Question

When I read about generic programming, often, are used this two terms:

Are there difference between them?

Yes, depending on the programming language. – Luiggi Mendoza Nov 14 '13 at 16:03 — Luiggi Mendoza, Nov 14 '13 at 16:03
Choose one language please. – Rohit Jain Nov 14 '13 at 16:03 — Rohit Jain, Nov 14 '13 at 16:03

score 5 · Accepted Answer · answered Nov 14 '13 at 16:04

5

In Java, in the following declaration

public class Foo<T> { ... }

Foo is a parameterized type. T is a type parameter.

answered Nov 14 '13 at 16:04

Is also an instance creation (i.e. Foo f = new Foo<>();) a parametrized type? – xdevel2000 Nov 15 '13 at 10:15
@xdevel2000 Generics in Java are a compile time concept (think of type erasure). When we speak of types, we mean array, class, interface, or enum types. So an instance is not a type of any sort. In your comment's code snippet, the `` part is a type _argument_, `Foo` is a _parameterized type_. – Sotirios Delimanolis Nov 15 '13 at 13:31

score 3 · Answer 2 · answered Nov 14 '13 at 16:05

3

Using C++ terminology:

A class template corresponds to a parameterised type - it becomes a type once you specify arguments for the parameters.

A type parameter is a parameter of a template, for which the arguments are types.

answered Nov 14 '13 at 16:05

score 2 · Answer 3 · answered Nov 14 '13 at 16:05

2

Generic types are also known as parametized types.

Type parameters refers to the types associated with a generic type. For example, with

Dictionary<T1, T2>

T1 and T2 are the type parameters.

answered Nov 14 '13 at 16:05

David Arno

3 Answers3