Modern C++ Design: Generic Programming and Design Patterns Applied

1. Policy-Based Class Design

This chapter describes policies and policy classes, important class design techniques that enable the creation of flexible, highly reusable libraries—as Loki aims to be. In brief, policy-based class design fosters assembling a class with complex behavior out of many little classes (called policies), each of which takes care of only one behavioral or structural aspect. As the name suggests, a policy establishes an interface pertaining to a specific issue. You can implement policies in various ways as long as you respect the policy interface.

Because you can mix and match policies, you can achieve a combinatorial set of behaviors by using a small core of elementary components.

Policies are used in many chapters of this ...