Visitor

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Visitor
Contributors Erich Gamma, Richard Helm, Ralph Johnson, John Vlissides
Last modification May 17, 2017
Source Gamma, Helm, Johnson & Vlissides (1995)[1], Visitor Pattern (2016)[2]
Pattern formats OPR Alexandrian
Usability
Learning domain
Stakeholders

Represent an operation to be performed on the elements of an object structure. Visitor lets you define a new operation without changing the classes of the elements on which it operates.[1][2]


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  1. 1.0 1.1 Gamma, E., Helm, R., Johnson, R. & Vlissides, J. (1995). Design Patterns: elements of reusable object-oriented software. Addison-Wesley: Boston, MA.ISBN 0-201-63361-2.
  2. 2.0 2.1 Visitor Pattern. (2016). Retrieved October 4, 2016 from http://c2.com/cgi/wiki?VisitorPattern.