Design Patterns Explained

Singleton Pattern

The Singleton Pattern ensures that a class has only one instance and provides a global point of access to that instance.

Real-life Example: A printer spooler that manages all print jobs in a system. There should be only one printer spooler to manage all the print requests.

Factory Method Pattern

The Factory Method Pattern defines an interface for creating an object but allows subclasses to alter the type of objects that will be created.

Real-life Example: A car manufacturing plant where different types of cars (sedan, SUV, truck) are produced. Each type of car is created using the factory method.

Observer Pattern

The Observer Pattern defines a one-to-many dependency between objects so that when one object changes state, all its dependents are notified and updated automatically.

Real-life Example: A weather station that broadcasts weather updates to various devices like smartphones, smartwatches, and computers. All these devices act as observers and receive updates when the weather changes.

Strategy Pattern

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

Real-life Example: Payment processing systems that offer different payment methods like credit card, PayPal, and bank transfer. Each payment method is encapsulated as a strategy, and the user can choose any strategy to make a payment.

Decorator Pattern

The Decorator Pattern attaches additional responsibilities to an object dynamically. Decorators provide a flexible alternative to subclassing for extending functionality.

Real-life Example: Adding toppings to a pizza. You can have a base pizza object and then dynamically add toppings like cheese, pepperoni, or mushrooms without altering the base pizza class.