Curiously recurring template pattern: Difference between revisions

Revision as of 18:45, 22 November 2022

Revision as of 20:57, 28 March 2023

Line 58:

</syntaxhighlight>

In the above example, the function <code>Base<Derived>::implementationinterface()</code>, though ''declared'' before the existence of the <code>struct Derived</code> is known by the compiler (i.e., before <code>Derived</code> is declared), is not actually ''instantiated'' by the compiler until it is actually ''called'' by some later code which occurs ''after'' the declaration of <code>Derived</code> (not shown in the above example), so that at the time the function "implementation" is instantiated, the declaration of <code>Derived::implementation()</code> 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 }}</ref> This pattern is used extensively in the Windows [[Active Template Library|ATL]] and [[Windows Template Library|WTL]] libraries.