Strategy design pattern defines family of algorithms, encapsulates each one of it and allow to use them interchangeably. Strategy lets the algorithms vary independently from client that use it.
Pattern type - Behavioral
In a nutshell - strategy decouples implementation and usage by providing unified interface, which family of algorithms have to implement in order to use them interchangeably. This pattern works nicely with dependency injection.
Strategy focuses on a composition over inheritance in order to effectively reuse code.
In an implemented example, IShape interface is defined, providing methods getCircumference
and getArea. Interface is implemented by Circle and Rectangle classes, which
calculate area and circumference accordingly to class specific shapes.
ShapesBox is a class which object accepts list of IShape compatible objects and
implements method getShapesTotalArea. It iterates over list of objects and calls
getArea method on each of it, summing all values.
From ShapesBox perspective it doesnt's matter what's concrete object it is dealing with
as all of them implement unified interface.
Execute make to compile.