Behavioral Patterns

• Iterator is a behavioral design pattern that lets you traverse elements of a collection without exposing its underlying representation.
• Observer is a behavioral design pattern that lets you define a subscription mechanism to notify multiple objects about any events that happen to the object they’re observing.
• Command is a behavioral design pattern that turns a request into a stand-alone object that contains all information about the request.

  
  

  This transformation lets you pass requests as a method arguments, delay or queue a request’s execution, and support undoable operations.
• Template Method is a behavioral design pattern that defines the skeleton of an algorithm in the superclass but lets subclasses override specific steps of the algorithm without changing its structure.
• Strategy is a behavioral design pattern that lets you define a family of algorithms, put each of them into a separate class, and make their objects interchangeable.