Visitor

From Open Pattern Repository for Online Learning Systems
Jump to navigation Jump to search


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]


Context

Problem

Forces

Solution

Consequences

Benefits

Liabilities

Evidence

Literature

Discussion

Data

Applied evaluation

Related patterns

Example

References

  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.