Visitor design pattern

E679870

behavioral design pattern software design pattern

The Visitor design pattern is a behavioral software design pattern that lets you separate algorithms from the object structures they operate on, enabling new operations to be added without modifying the existing classes.

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Observed surface forms (1)

Surface form	Occurrences
Visitor pattern	2

Statements (53)

Predicate	Object
instanceOf	behavioral design pattern ⓘ software design pattern ⓘ
applicableWhen	classes defining the object structure rarely change ⓘ many unrelated operations need to be performed on objects in a structure ⓘ object structure is relatively stable ⓘ
belongsTo	Gang of Four design patterns NERFINISHED ⓘ
benefit	can simplify maintenance of complex operations ⓘ facilitates adding cross-cutting operations ⓘ improves separation of concerns between data structures and operations ⓘ keeps related operations together in visitor classes ⓘ supports accumulation of state during traversal ⓘ
commonUseCase	code analysis tools ⓘ compilers and abstract syntax tree processing ⓘ document object model traversal ⓘ operations on hierarchical data structures ⓘ
coreMechanism	double dispatch ⓘ
definesCollaborationBetween	Element ⓘ ObjectStructure ⓘ Visitor NERFINISHED ⓘ
describedIn	Design Patterns: Elements of Reusable Object-Oriented Software NERFINISHED ⓘ
drawback	adding a new element class requires changes to all existing visitors ⓘ can break encapsulation by exposing element internals to visitors ⓘ increases coupling between visitors and element classes ⓘ
enables	adding new operations by creating new visitor classes ⓘ
hasAlias	Visitor ⓘ
hasCategory	behavioral pattern ⓘ
introducedBy	Erich Gamma NERFINISHED ⓘ John Vlissides NERFINISHED ⓘ Ralph Johnson NERFINISHED ⓘ Richard Helm NERFINISHED ⓘ
keyMethod	accept() ⓘ visit() ⓘ
oftenUsedWith	composite pattern ⓘ interpreter pattern NERFINISHED ⓘ iterator pattern ⓘ
primaryIntent	enable adding new operations without modifying existing classes ⓘ separate algorithms from object structures ⓘ
relatedConcept	double dispatch ⓘ open/closed principle NERFINISHED ⓘ separation of concerns ⓘ
requires	modifying visitor interface when adding new element types ⓘ
supports	open/closed principle ⓘ
supportsLanguageFeature	emulation of multiple dispatch in single-dispatch languages ⓘ
tradeOff	easy to add new operations but hard to add new element classes ⓘ
typicalLanguageContext	object-oriented programming ⓘ
typicalStructureElement	ConcreteElement class ⓘ ConcreteVisitor class NERFINISHED ⓘ Element interface ⓘ ObjectStructure class ⓘ Visitor interface ⓘ
usedFor	defining new operations on object structures ⓘ performing operations on elements of an object structure ⓘ traversing complex object structures ⓘ

Referenced by (4)

Full triples — surface form annotated when it differs from this entity's canonical label.

Visitor → alsoKnownAs → Visitor design pattern ⓘ

this entity surface form: Visitor pattern

Composite → oftenUsedWith → Visitor design pattern ⓘ

Composite → relatedTo → Visitor design pattern ⓘ

Interpreter → relatedTo → Visitor design pattern ⓘ

this entity surface form: Visitor pattern