Each desired customization is captured as one or more constraints in a very small class known as a "policy class". Our paper will show the straightforward steps needed to adapt a configuration class to support policies, to create a policy base class that works correctly with the configuration class, and to write new policy classes as required by the application. Once this has been done, applying a customization is easy: add it to a list of policies within the object being constrained. In this way, customizations can be neatly encapsulated, given descriptive names, and applied or removed easily at runtime.
