PHP Design Patterns: Implementation Guide

PHP design patterns provide reusable solutions to common programming problems, improving code readability, maintainability, and scalability. Commonly used patterns include: creational pattern: factory method, singleton structural pattern: adapter, bridge, combined behavioral pattern: command, observer, strategy

## PHP Design Patterns: Implementation Guide

Introduction

Design patterns are reusable solutions to common programming problems. They help improve code readability, maintainability, and scalability.

Why use design patterns?

Provides proven solutions to common programming problems.
• Improve the readability and maintainability of the code.
• Promote code reuse and extensibility.

Commonly used design patterns in PHP

Creative pattern:

• Factory Methods: Create objects of different types without specifying their concrete classes.
• Single case: Ensures that only one instance of a specific class exists.

Structural pattern:

• Adapter: Adapt one interface to another interface.
• Bridging: Separate abstraction from implementation.
• Composition: Create complex objects by combining objects.

Behavioral mode:

• Command: Encapsulate the request as an object.
• Observers: Allows objects to subscribe to and respond to events.
• Strategy: Encapsulate algorithms or behaviors into interchangeable classes.

Practical case: singleton pattern

Question: How to ensure that a class has only one instance?

Solution:

class Singleton {
  private static $instance;

  private function __construct() {}

  public static function getInstance() {
    if (!isset(self::$instance)) {
      self::$instance = new Singleton();
    }
    return self::$instance;
  }
}

Usage example:

$instance1 = Singleton::getInstance();
$instance2 = Singleton::getInstance();

if ($instance1 === $instance2) {
  echo "Same instance";
}

Other design patterns and usage

PatternUsage##Factory MethodAdaptersBridgingCompositionCommandsobservers Strategy

Create different types of products
Adapt one or more classes to another interface
Separate abstraction and implementation so that they can vary independently
Combining smaller objects to create more complex objects
Encapsulate requests as objects to loosely couple senders and receivers
allow objects to subscribe to and respond to events
Encapsulate algorithms or behaviors into interchangeable classes

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