PHP version

The book is written for JAVA application. Since I am learning design's patterns I decided to "translate" it to PHP

Head First Design Patterns

Strategy Pattern

Defines a family of algorithms, encapsulates each one, and makes them interchangeable. Strategy lets the algorithm vary independently from clients that use it.

Design Principle #1

Identify the aspect's of your application that vary and separate them from what stays the same.

Design Principle #2

Program to an interface, not an implementation.

Design Principle #3

Favor composition over inheritance