PHP Object-oriented programming design patterns have always been a hot topic studied by developers. In this article, PHP editor Strawberry will delve into the SOLID principles to help readers understand and apply these design principles. The SOLID principle is the cornerstone of object-oriented programming, including the single responsibility principle, the open and closed principle, the Liskov substitution principle, the interface isolation principle and the dependency inversion principle. By learning and practicing these principles, developers can write more flexible, maintainable, and scalable PHP code.
class User { private $id; private $name; private $email; public function __construct($id, $name, $email) { $this->id = $id; $this->name = $name; $this->email = $email; } public function getId() { return $this->id; } public function getName() { return $this->name; } public function getEmail() { return $this->email; } } class UserRepository { private $connection; public function __construct($connection) { $this->connection = $connection; } public function save(User $user) { $stmt = $this->connection->prepare("INSERT INTO users (name, email) VALUES (?, ?)"); $stmt->execute([$user->getName(), $user->getEmail()]); } public function find($id) { $stmt = $this->connection->prepare("SELECT * FROM users WHERE id = ?"); $stmt->execute([$id]); $result = $stmt->fetch(); if ($result) { return new User($result["id"], $result["name"], $result["email"]); } return null; } }
interface Shape { public function getArea(); } class Rectangle implements Shape { private $width; private $height; public function __construct($width, $height) { $this->width = $width; $this->height = $height; } public function getArea() { return $this->width * $this->height; } } class Circle implements Shape { private $radius; public function __construct($radius) { $this->radius = $radius; } public function getArea() { return pi() * $this->radius ** 2; } } class ShapeCalculator { public function calculateTotalArea($shapes) { $totalArea = 0; foreach ($shapes as $shape) { $totalArea += $shape->getArea(); } return $totalArea; } }
class Animal { public function eat() { echo "Animal is eating."; } } class Dog extends Animal { public function bark() { echo "Dog is barking."; } } class Cat extends Animal { public function meow() { echo "Cat is meowing."; } } function feedAnimal(Animal $animal) { $animal->eat(); } feedAnimal(new Dog()); // prints "Dog is eating." feedAnimal(new Cat()); // prints "Cat is eating."
interface Printable { public function print(); } interface Scannable { public function scan(); } interface Faxable { public function fax(); } class Printer implements Printable { public function print() { echo "Printer is printing."; } } class Scanner implements Scannable { public function scan() { echo "Scanner is scanning."; } } class FaxMachine implements Faxable { public function fax() { echo "Fax machine is faxing."; } } class MultifunctionDevice implements Printable, Scannable, Faxable { public function print() { echo "Multifunction device is printing."; } public function scan() {
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