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

16.6. Information Expert (or Expert)

Assign a responsibility to the information expert—the class that has the information necessary to fulfill the responsibility.

Solution

What is a general principle of assigning responsibilities to objects?

Problem

A Design Model may define hundreds or thousands of software classes, and an application may require hundreds or thousands of responsibilities to be fulfilled. During object design, when the interactions between objects are defined, we make choices about the assignment of responsibilities to software classes. Done well, systems tend to be easier to understand, maintain, and extend, and there is more opportunity to reuse components in future applications.

In the NextGEN POS application, some class ...