Curiously recurring template pattern: Difference between revisions

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The '''curiously recurring template pattern''' ('''CRTP''') is a [[C++]] idiom in which a class <code>X</code> derives from a class template instantiation using <code>X</code> itself as template argument. The name of this idiom was coined by [[Jim Coplien]]<ref>{{refcite journal | author=Coplien, James O. | title=Curiously Recurring Template Patterns | journal=C++ Report | year=1995, February | pages=24–27}}</ref>, who had observed it in some of the earliest [[C++]] template code.

== General form ==

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Some use cases for this pattern are [[Template metaprogramming#Static_polymorphismStatic polymorphism|static polymorphism]], and other metaprogramming techniques such as those described by [[Andrei Alexandrescu{{ref|Alexandrescu}}]] in [[Modern C++ Design]] <ref>[[Andrei Alexandrescu]]: ''[[Modern C++ Design]]: Generic Programming and Design Patterns Applied'', Addison-Wesley, ISBN 3-8266-1347-3</ref>.

== Static polymorphism ==

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==In other languages==

The CRTP makes an appearance in the [[Java language|Java programming language]] standard library where the [[Enumerated type|Enum]] class is defined as <code>Enum&lt;T extends Enum&lt;T&gt;&gt;</code>. Java programmers use the CRTP in practice when they write a comparable class: <code>class X implements Comparable&lt;X&gt;</code>.

==See also==

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==References==

<references/>

* {{note|Coplien}}{{cite journal | author=Coplien, James O. | title=Curiously Recurring Template Patterns | journal=C++ Report | year=1995, February | pages=24–27}}

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* {{note|Alexandrescu}}[[Andrei Alexandrescu]]: ''[[Modern C++ Design]]: Generic Programming and Design Patterns Applied'', Addison-Wesley, ISBN 3-8266-1347-3

* {{note|Abrahams}}[[David Abrahams]], Aleksey Gurtovoy: ''C++ Template Metaprogramming: Concepts, Tools, and Techniques from Boost and Beyond'', Addison-Wesley, ISBN 0-321-22725-5

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[[Category:Software design patterns]]