Implementation of association as an object

• Implement as a separate association object, independent of either class, as in Figure. An association object is a group of pairs of associated objects stored in the single variable-size object. For efficiency, we can implement an association object using two dictionary objects, one for forward direction and other for backward direction. This concept is useful for extending predefined classes from a library that cannot be modified. Distinct association objects are also helpful for sparse associations. In sparse associations mainly objects of the classes do not participate as space is used only for actual links.

Figure: Implementation of association as an object