DesginPatterns

Table Of Contents

• Behavioral

  • Observer Pattern

• Strcutural

  • Adapter Pattern

Behavioral :

Observer Pattern

• One object notifies other objects about its state change.
• It is a one-to-many relationship.
• When the state of one object changes, other object which are subscribed to it gets notified about the state change.
• Observable protocol has three abstract methods :
  • add(observerX) : to add an observer.
  • remove(observerX) : to remove a specific observer.
  • notify() : to notify all observers.

Code example here

Implementation

Strcutural :

Adapter Pattern

• Named also Wrapper.
• Allows objects with incompatible interfaces to collaborate.
• lets you create a middle-layer class that serves as a translator between your code and a legacy class, a 3rd-party class or any other class with a weird interface.
• Do not add an additional behavior.

Code example here

Implementation