Association (object-oriented programming): Difference between revisions

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In [[object-oriented programming]], '''association''' defines a relationship between classes of objects that allows one object instance to cause another to perform an action on its behalf. This relationship is [[Unified Modeling Language#Structure diagrams|structural]], because it specifies that objects of one kind are connected to objects of another and does not represent [[Unified Modeling Language#Behavior diagrams|behaviour]].

[[Image:UnidirectionalAssociationAssociation.pngJPG|thumb|225px|Top: A bidirectional association<br/><br/>Middle: An association is bidirectional, although it may be limited to just one direction by adorning some end with an arrowhead pointing to the direction of traversal.<br/><br/>Bottom: Association is prohibited]]

[[Image:BidirectionalAssociation.png|thumb|225px|A bidirectional association]]

[[Image:UnidirectionalAssociation.png|thumb|225px|An association is bidirectional, although it may be limited to just one direction by adorning some end with an arrowhead pointing to the direction of traversal.]]

In generic terms, the [[Causality|causation]] is usually called "sending a message", "invoking a [[Method (computer science)|method]]" or "calling a [[member function]]" to the controlled object. Concrete implementation usually requires the requesting object to invoke a ''method'' or ''member function'' using a [[Reference (computer science)|reference]] or pointer to the memory ___location of the controlled object.