Curiously recurring template pattern: Difference between revisions

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==History==

The technique was formalized in 1989 as "''F''-bounded quantification."<ref>{{cite web|url=http://staff.ustc.edu.cn/~xyfeng/teaching/FOPL/lectureNotes/CookFBound89.pdf|title=F-Bounded Polymorphism for Object-Oriented Programming|author=William Cook|date=1989|display-authors=etal}}</ref> The name "CRTP" was independently coined by [[Jim Coplien]] in 1995,<ref>{{cite journal | author=Coplien, James O. | title=Curiously Recurring Template Patterns | journal=C++ Report | date=February 1995 | pages=24–27 | url=http://sites.google.com/a/gertrudandcope.com/info/Publications/InheritedTemplate.pdf}}</ref> who had observed it in some of the earliest [[C++]] template code

as well as in code examples that Timothy Budd created in his multiparadigm language Leda.<ref>{{cite book | first=Timothy | last=Budd | authorlink=Timothy Budd | title=Multiparadigm programming in Leda | publisher=Addison-Wesley | isbn=0-201-82080-3 | year=1994| title-link=Multiparadigm programming in Leda }}</ref> It is sometimes called "Upside-Down Inheritance"<ref>{{Cite web|url=http://www.apostate.com/programming/atlupsidedown.html |title=Apostate Café: ATL and Upside-Down Inheritance |date=2006-03-15 |access-date=2016-10-09 |url-status=bot: unknown |archiveurl=https://web.archive.org/web/20060315072824/http://www.apostate.com/programming/atlupsidedown.html |archivedate=15 March 2006 }}</ref><ref>{{Cite web|url=http://archive.devx.com/free/mgznarch/vcdj/1999/julmag99/atlinherit1.asp |title=ATL and Upside-Down Inheritance |date=2003-06-04 |access-date=2016-10-09 |url-status=bot: unknown |archiveurl=https://web.archive.org/web/20030604104137/http://archive.devx.com/free/mgznarch/vcdj/1999/julmag99/atlinherit1.asp |archivedate=4 June 2003 }}</ref> due to the way it allows class hierarchies to be extended by substituting different base classes.

The Microsoft Implementation of CRTP in [[Active Template Library]] (ATL) was independently discovered, also in 1995, by Jan Falkin, who accidentally derived a base class from a derived class. Christian Beaumont first saw Jan's code and initially thought it could not possibly compile in the Microsoft compiler available at the time. Following the revelation that it did indeed work, Christian based the entire ATL and [[Windows Template Library]] (WTL) design on this mistake.{{Citation needed|date=August 2018}}