PHP服务类依赖注入与静态方法：选择合适的调用策略

class EmailService
{
    private EntityManagerInterface $entityManager;
    private EmailFactory $emailFactory;

    public function __construct(EntityManagerInterface $em, EmailFactory $emailFactory)
    {
        $this->entityManager = $em;
        $this->emailFactory = $emailFactory;
    }

    public function sendPaymentEmail(string $sender, User $user, string $templateKey): bool
    {
        // 此方法通常会使用 $this->emailFactory 来创建邮件
        // 并且可能使用 $this->entityManager 来持久化邮件日志等
        // 例如：
        // $email = $this->emailFactory->createEmail($sender, $user->getEmail(), $templateKey);
        // ... 发送邮件逻辑 ...
        // $this->entityManager->persist(new EmailLog($email));
        // $this->entityManager->flush();
        return true;
    }
}

class PaymentService
{
    // ... 其他属性和方法 ...

    public function sendPaymentEmail(User $user)
    {
        // 错误：EmailService 构造函数需要参数
        $emailService = new EmailService(); // 这里会抛出 "Too few arguments" 错误

        $sender = 'no-reply@example.com'; // 假设从配置获取
        return $emailService->sendPaymentEmail($sender, $user, 'customer_home');
    }
}

// app/src/Service/PaymentService.php
namespace App\Service;

use App\Entity\User;
use App\Service\EmailService; // 确保引入 EmailService

class PaymentService
{
    private EmailService $emailService;
    // 假设还有其他依赖，例如 Twig
    private \Twig\Environment $twig;

    // 通过构造函数注入 EmailService 实例
    public function __construct(EmailService $emailService, \Twig\Environment $twig)
    {
        $this->emailService = $emailService;
        $this->twig = $twig;
    }

    public function sendPaymentEmail(User $user): bool
    {
        $sender = $this->twig->getGlobals()['email_no_reply'] ?? 'no-reply@example.com';
        // 直接使用已注入的 emailService 实例
        return $this->emailService->sendPaymentEmail($sender, $user, 'customer_home');
    }
}

class EmailService
{
    // ... 构造函数和非静态属性保持不变 ...

    // 假设有一个真正不需要实例状态的工具方法
    public static function isValidEmailAddress(string $email): bool
    {
        return filter_var($email, FILTER_VALIDATE_EMAIL) !== false;
    }

    // 如果 EmailService::sendPaymentEmail *真的*不需要 $this->entityManager 或 $this->emailFactory，
    // 才能考虑设为静态。但通常它需要，所以这只是一个假设性示例。
    // 如果它被设为静态，它将无法访问 $this->emailFactory。
    // public static function sendPaymentEmail(string $sender, User $user, string $templateKey): bool
    // {
    //     // 错误：无法访问非静态属性 $this->emailFactory
    //     // $email = self::emailFactory->createEmail(...);
    //     return true;
    // }
}

class PaymentService
{
    // ... 构造函数和属性 ...

    public function processUserEmail(string $email): string
    {
        if (EmailService::isValidEmailAddress($email)) { // 直接通过类名调用静态方法
            return "Email address is valid.";
        } else {
            return "Invalid email address.";
        }
    }
}