PHP class decorator

README.md

PHP class decorator

假设我们现在要给 BaseClass 添加更多的功能：

/**
 * @mixin BaseClass
 * @extends parent<BaseClass>
 * ↑ 添加这些 PHPDoc 注释会很有帮助，它们让 IDE 给出正确的提示
 */
class MyClassPlus extends BaseDecorator {
  // 务必手动调用一下这个方法，以确保静态方法被代理
  public static function __callStatic($method, $args) {
    return self::callStaticOn(BaseClass::class, $method, ...$args);
  }

  // 然后就可以在这里添加你需要的实例方法了
  public function someMethod() {
    // do something
  }
}

现在，你可以快乐地在任意位置使用：

$polyfill = new MyClassPlus($instance);
$polyfill->someMethod();

BaseDecorator.php

<?php

declare(strict_types=1);

/**
 * @template T of object
 * @mixin T
 */
class BaseDecorator {
  /** @var T */
  private object $instance;

  /** @param T $instance */
  public function __construct(object $instance) {
    $this->instance = $instance;
  }

  /** @return mixed */
  public function __call(string $name, array $arguments): mixed {
    if (is_callable([$this->instance, $name])) {
      // callable 检查可以排除 protected/private 方法造成的错误
      return $this->instance->{$name}(...$arguments);
    }
    throw new BadMethodCallException(
      sprintf('Method %s::%s() is not accessible or does not exist.', $this->instance::class, $name)
    );
  }

  /**
   * 静态方法调用工厂
   * @template C of object
   * @param class-string<C> $class
   * @param string          $method
   * @param mixed           ...$args
   * @return mixed
   */
  public static function callStaticOn(string $class, string $method, mixed ...$args): mixed {
    if (is_callable([$class, $method])) {
      return $class::$method(...$args);
    }
    throw new BadMethodCallException(
      sprintf('Static method %s::%s() is not accessible or does not exist.', $class, $method)
    );
  }

  /** @return mixed */
  public function __get(string $name): mixed {
    return $this->instance->$name;
  }

  public function __isset(string $name): bool {
    return isset($this->instance->$name);
  }

  /** @return T */
  protected function getRealInstance(): object {
    return $this->instance;
  }
}