Applying UML and Patterns: An Introduction to Object-Oriented Analysis and Design and the Unified Process, Second Edition

16.7. Creator

Assign class B the responsibility to create an instance of class A if one or more of the following is true:

• B aggregates A objects.

• B contains A objects.

• B records instances of A objects.

• B closely uses A objects.

• B has the initializing data that will be passed to A when it is created (thus B is an Expert with respect to creating A).

Solution

B is a creator of A objects.

If more than one option applies, prefer a class B which aggregates or contains class A.

Who should be responsible for creating a new instance of some class?

Problem

The creation of objects is one of the most common activities in an object-oriented system. Consequently, it is useful to have a general principle for the assignment of creation responsibilities. Assigned ...