Mixin
In object-oriented programming languages, a mixin is a class that contains a combination of methods from other classes. How such a combination is done depends on the language. If a combination contains all methods of combined classes, it is equivalent to multiple inheritance. Mixins are sometimes described as being "included" rather than "inherited".
Mixins encourage code reuse and can be used to avoid the inheritance ambiguity that multiple inheritance can cause (the "diamond problem"), or to work around lack of support for multiple inheritance in a language. A mixin can also be viewed as an interface with implemented methods.