Controlling Method Access

Functionality of a method can be provided or denied to clients by making methods modal.
Two modes (enabled and disabled) mean that availability of services and resources to client code is controlled by varying the mode.
This is dynamic - the availability of methods can change during client program execution (c.f. Java Security Manager and others).
Client code blocks when invoking a disabled method, until it is made available again.

Functionality of a method can be provided or denied to clients by making methods modal.