Mixin

A 'mixin' is a class that offers functionality to be inherited by a subclass, but is not meant to stand alone. Inheriting from a mixin is not a form of specialisation but is rather a means to collect functionality. A subclass may even choose to inherit most or all of its functionality by inheriting from one or more mixins through multiple inheritance. A mixin can defer definition and binding of methods until runtime, though attributes and instantiation parameters are still defined at compile time.