SWPatterns.com

Snapshot - PHP

The Snapshot pattern allows capturing and restoring the internal state of an object. This is useful for implementing features like undo/redo, transaction rollback, or saving game progress. The code defines a Report class representing the object whose state needs to be saved. A ReportSnapshot class stores the state of …

Policy - PHP

The Policy pattern encapsulates complex business logic or rules into separate classes, allowing for flexibility and maintainability. Instead of embedding these rules directly within an object, the object delegates the decision-making to a Policy object. This promotes the Single Responsibility Principle and makes it …

Specification - PHP

The Specification pattern is a behavioral design pattern that defines a way to represent complex conditions using boolean expressions. It allows you to decouple the logic that determines if something is valid from the object it’s being applied to. This promotes reusability and composability of validation rules. …

Null Object - PHP

The Null Object pattern provides a default object with no-op behavior to handle cases where an object is expected but may not exist. This avoids null checks throughout the code, improving readability and reducing potential errors. The example implements a Customer interface with methods like getName and getOrders. …

Visitor - PHP

The Visitor pattern allows you to define a new operation without modifying the classes of the objects on which it operates. It’s achieved by moving the operation to a separate “visitor” class that accepts different object types as input. This promotes the Open/Closed Principle.

The code defines a …

Template Method - PHP

The Template Method pattern defines the skeleton of an algorithm in a base class, deferring some steps to subclasses. It allows subclasses to redefine certain steps of an algorithm without changing the algorithm’s structure. This promotes code reuse and avoids duplication.

The PHP example defines an abstract …

Strategy - PHP

The Strategy pattern defines a family of algorithms, encapsulates each one, and makes them interchangeable. It allows an algorithm to vary independently from the clients that use it. This implementation uses an interface PaymentStrategy to define a common method for making payments. Concrete strategies like …

State - PHP

The State pattern allows an object to alter its behavior when its internal state changes. It encapsulates each state as a separate class, making it easy to add new states without modifying the context object. This promotes the Open/Closed Principle.

The code defines a TrafficLight context and states (Red, Yellow, Green …

Observer - PHP

The Observer pattern defines a one-to-many dependency between objects. When the state of an object (the subject) changes, all its dependent objects (the observers) are notified and updated automatically. This promotes loose coupling, allowing subjects and observers to change independently.

The code implements this with …

Memento - PHP

The Memento pattern is a behavioral pattern that captures and externalizes the internal state of an object without violating encapsulation. It allows restoring an object to its previous state (saving and loading states). This implementation uses a Memento class to hold the state, an Originator class whose state is …