Links

An association between objects is called a link. An object can have links to other objects as part of its required interface. Through such links, the object can request services of or send events to another object.

Links bind roles, which are the structural slots through which an object can refer to its links. By default, a role is named its<object>, where <object> is the name of the peer on the other end of the link.

Links can be symmetric or directional. With a symmetric link, both objects know each other, implying two roles. With directional links, only one object has access to its peer through a single role. See Symmetric associations and Aggregations and compositions for more information.

Roles have multiplicity. A multiplicity of one means that the link connects an object to only one other object. The default multiplicity is set by the General::Relations::DefaultMultiplicity property.

If a link connects an object to more than one other object (multiplicity greater than 1), that link is implemented by default as an array. In addition, a role can contain references in the form of pointers, facilitating access to several members within the group.


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