Curiously recurring template pattern: Difference between revisions

Revision as of 17:30, 23 April 2021

Revision as of 01:09, 11 August 2021

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In the above example, note in particular that the function Base<Derived>::interfaceimplementation(), though ''declared'' before the existence of the struct Derived is known by the compiler (i.e., before Derived is declared), is not actually ''instantiated'' by the compiler until it is actually ''called'' by some later code which occurs ''after'' the declaration of Derived (not shown in the above example), so that at the time the function "implementation" is instantiated, the declaration of Derived::implementation() is known.

This technique achieves a similar effect to the use of [[virtual function]]s, without the costs (and some flexibility) of [[dynamic polymorphism]]. This particular use of the CRTP has been called "simulated dynamic binding" by some.<ref>{{cite web | url=http://www.pnotepad.org/devlog/archives/000083.html | title=Simulated Dynamic Binding | date=7 May 2003 | accessdate=13 January 2012 | url-status=dead | archiveurl=https://web.archive.org/web/20120209045146/http://www.pnotepad.org/devlog/archives/000083.html | archivedate=9 February 2012 | df=dmy-all }}</ref> This pattern is used extensively in the Windows [[Active Template Library|ATL]] and [[Windows Template Library|WTL]] libraries.