Encapsulation (computer programming): Difference between revisions

Revision as of 05:09, 22 July 2016

Revision as of 07:55, 22 July 2016

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In [[programming languaglanguages]], <!-- [[object-oriented programming language]]--> <!-- and related fields, like [[OODMBS]],--> '''encapsulation''' is used to refer to one of two related but distinct notions, and sometimes to the combination<ref>Michael Lee Scott, ''Programming language pragmatics'', Edition 2, Morgan Kaufmann, 2006, ISBN 0-12-633951-1, p. 481: "Encapsulation mechanisms enable the programmerprogrammer to group data and the subroutines that operate on them together in one place, and to hide irrelevant details from the users of an abstraction."</ref><ref name=Dale>Nell B. Dale, Chip Weems, ''Programming and problem solving with Java'', Edition 2, Jones & Bartlett Publishers, 2007, ISBN 0-7637-3402-0, p. 396</ref> thereof:

* A language mechanism for restricting direct access to some of the [[object (computer science)|object]]'s components.<ref>[[John C. Mitchell]], ''Concepts in programming languages'', Cambridge University Press, 2003, ISBN 0-521-78098-5, p.522</ref><ref name=Pierce>{{cite book|last=Pierce|first=Benjamin|authorlink=Benjamin C. Pierce|title=[[Types and Programming Languages]]|publisher=MIT Press|year=2002|isbn=0-262-16209-1}} p. 266</ref>

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Hiding the internals of the object protects its integrity by preventing users from setting the internal data of the component into an invalid or inconsistent state. A supposed benefit of encapsulation is that it can reduce system complexity, and thus increase [[robustness (computer science)|robustness]], by allowing the developer to limit the inter-dependencies between software components{{Citation needed|date=April 2014}}.

Almost always, there is a way to override such protection &ndash; usually via [[Reflection Reflection_(computer programmingcomputer_programming)|reflection]] API (Ruby, Java, C#, etc.), sometimes by mechanism like [[name mangling]] ([[Python (programming language)|Python]]), or special keyword usage like <code>friend</code> in C++.

Below is an example in [[C Sharp (programming language)|C#]] that shows how access to a data field can be restricted through the use of a <code>private</code> keyword: