Composition over inheritance: Difference between revisions

Revision as of 17:35, 3 June 2022

Revision as of 01:42, 28 June 2022

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Composition relation is more flexible as it may be changed on runtime, while sub-typing relations are static and need recompilation in many languages.

Some languages, notably [[Go (programming language)|Go]]<ref>{{cite web |url=https://commandcenter.blogspot.com/2012/06/less-is-exponentially-more.html |title=Less is exponentially more |last1=Pike |first1=Rob |date=2012-06-25 |accessdate=2016-10-01 }}</ref> and [[Rust (programming language)|Rust]]{{cncitation needed|date=December 2021}}, use type composition exclusively.

==Drawbacks==

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A 2013 study of 93 open source Java programs (of varying size) found that:

{{quoteblockquote|While there is not huge opportunity to replace inheritance with composition (...), the opportunity is significant (median of 2% of uses [of inheritance] are only internal reuse, and a further 22% are only external or internal reuse).

Our results suggest there is no need for concern regarding abuse of inheritance (at least in open-source Java software), but they do highlight the question regarding use of composition versus inheritance. If there are significant costs associated with using inheritance when composition could be used, then our results suggest there is some cause for concern.|Tempero ''et al.'', "What programmers do with inheritance in Java"<ref>{{cite conference |last1=Tempero |first1=Ewan |first2=Hong Yul |last2=Yang |first3=James |last3=Noble |title=ECOOP 2013 – Object-Oriented Programming |chapter=What programmers do with inheritance in Java |conference=ECOOP 2013–Object-Oriented Programming |year=2013 |pages=577–601 |chapter-url=https://www.cs.auckland.ac.nz/~ewan/qualitas/studies/inheritance/TemperoYangNobleECOOP2013-pre.pdf |doi=10.1007/978-3-642-39038-8_24 |isbn=978-3-642-39038-8 |series=Lecture Notes in Computer Science |volume=7920}}</ref>}}