每個軟體工程師都應該知道的頂級設計模式

PHP，特別是 PHP 中的屬性、枚舉和唯讀屬性等現代功能，非常適合實現設計模式。以下是每個軟體工程師都應該了解的五個基本模式。

---

1. 單例模式

確保一個類別只有一個實例。

final class Config 
{
    private static ?Config $instance = null;

    private function __construct(public readonly array $settings) {}

    public static function getInstance(): Config 
    {
        return self::$instance ??= new Config(['env' => 'production']);
    }
}

// Usage
$config = Config::getInstance();
echo $config->settings['env']; // Output: production

---

2. 工廠模式

集中物件建立邏輯。

class DatabaseFactory 
{
    public static function create(string $type): Database 
    {
        return match ($type) {
            'mysql' => new MySQLDatabase(),
            'postgres' => new PostgresDatabase(),
            default => throw new InvalidArgumentException("Unknown database type"),
        };
    }
}

interface Database { public function connect(): void; }
class MySQLDatabase implements Database { public function connect() { echo "MySQL connected"; } }
class PostgresDatabase implements Database { public function connect() { echo "Postgres connected"; } }

// Usage
$db = DatabaseFactory::create('mysql');
$db->connect(); // Output: MySQL connected

---

3. 觀察者模式

通知多個物件有關狀態變更的資訊。

class Event 
{
    private array $listeners = [];

    public function attach(callable $listener): void { $this->listeners[] = $listener; }
    public function trigger(string $data): void { foreach ($this->listeners as $listener) $listener($data); }
}

// Usage
$event = new Event();
$event->attach(fn($data) => print "Listener 1: $data\n");
$event->attach(fn($data) => print "Listener 2: $data\n");

$event->trigger("Event triggered"); 
// Output:
// Listener 1: Event triggered
// Listener 2: Event triggered

---

4. 裝飾器模式

動態新增行為給物件。

interface Text { public function render(): string; }

class PlainText implements Text 
{
    public function __construct(private string $text) {}
    public function render(): string { return $this->text; }
}

class BoldText implements Text 
{
    public function __construct(private Text $text) {}
    public function render(): string { return "<b>" . $this->text->render() . "</b>"; }
}

// Usage
$text = new BoldText(new PlainText("Hello, World!"));
echo $text->render(); // Output: <b>Hello, World!</b>

---

5. 策略模式

運行時在演算法之間切換。

interface PaymentStrategy { public function pay(float $amount): void; }

class CreditCardPayment implements PaymentStrategy 
{
    public function pay(float $amount): void { echo "Paid $amount with Credit Card\n"; }
}

class PayPalPayment implements PaymentStrategy 
{
    public function pay(float $amount): void { echo "Paid $amount via PayPal\n"; }
}

class PaymentProcessor 
{
    public function __construct(private PaymentStrategy $strategy) {}

    public function execute(float $amount): void 
    {
        $this->strategy->pay($amount);
    }
}

// Usage
$processor = new PaymentProcessor(new PayPalPayment());
$processor->execute(100.00); // Output: Paid 100 via PayPal

---

這些模式解決了現實世界的問題，是編寫可維護和可擴展的應用程式的基礎。

哪種模式與您目前的專案產生共鳴？快來評論裡討論吧！ ？

以上是每個軟體工程師都應該知道的頂級設計模式的詳細內容。更多資訊請關注PHP中文網其他相關文章！