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

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

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