Compositionis a method of reuse in which new functionality is obtained by creating an object composed of other objects. The new functionality is obtained by delegating functionality to one of the objects being composed. Sometimes it is called aggregation or containment, although some authors give special meanings to these terms. For example: Aggregation – when [...]
Abstraction arises from a recognition of similarities between certain objects, situations, or processes in the real world, and the decision to concentrate upon those similarities and to ignore for the time being the differences. — Tony Hoare An abstraction denotes the essential characteristics of an object that distinguish it from all other kinds of objects [...]
The GoF design patterns are in the middle of these levels of abstraction A design pattern names, abstracts, and identifies key aspects of a common design structure that makes it useful for creating a reusable object-oriented design. The GoF design patterns are descriptions of communicating objects and classes that are customized to solve a general [...]