php 实现before事件

在 PHP 中实现类似 "before" 事件（即在某个操作执行前触发的逻辑），可以通过以下方法实现：

使用面向对象设计模式

通过装饰器模式或钩子（Hook）机制，在目标方法执行前插入逻辑：

class EventDispatcher {
    private $beforeCallbacks = [];

    public function before(callable $callback) {
        $this->beforeCallbacks[] = $callback;
    }

    public function execute() {
        foreach ($this->beforeCallbacks as $callback) {
            call_user_func($callback);
        }
        // 主逻辑执行
        echo "Main logic executed\n";
    }
}

$dispatcher = new EventDispatcher();
$dispatcher->before(function() {
    echo "Before event triggered\n";
});
$dispatcher->execute();

使用魔术方法 __call

通过魔术方法拦截方法调用，在方法执行前触发事件：

class BeforeEventExample {
    public function __call($name, $arguments) {
        if (method_exists($this, 'before'.$name)) {
            call_user_func([$this, 'before'.$name]);
        }
        return call_user_func_array([$this, $name], $arguments);
    }

    protected function beforeAction() {
        echo "Before action triggered\n";
    }

    protected function action() {
        echo "Main action executed\n";
    }
}

$example = new BeforeEventExample();
$example->action();

使用 trait 实现复用

通过 trait 封装 before 事件逻辑，实现多类复用：

trait BeforeEventTrait {
    protected $beforeHandlers = [];

    public function before($event, callable $handler) {
        $this->beforeHandlers[$event][] = $handler;
    }

    protected function triggerBefore($event) {
        if (isset($this->beforeHandlers[$event])) {
            foreach ($this->beforeHandlers[$event] as $handler) {
                $handler();
            }
        }
    }
}

class Example {
    use BeforeEventTrait;

    public function doSomething() {
        $this->triggerBefore('doSomething');
        echo "Main operation\n";
    }
}

$example = new Example();
$example->before('doSomething', function() {
    echo "Before hook\n";
});
$example->doSomething();

使用 AOP（面向切面编程）

通过第三方库如 Go! AOP 实现更专业的切面编程：

// 需要安装 goaop/framework
use Go\Core\AspectContainer;
use Go\Core\AspectKernel;

class BeforeAspect implements \Go\Aop\Aspect {
    public function beforeMethod(\Go\Aop\Intercept\MethodInvocation $invocation) {
        echo "Before " . $invocation->getMethod()->getName() . " execution\n";
    }
}

class ApplicationAspectKernel extends AspectKernel {
    protected function configureAop(AspectContainer $container) {
        $container->registerAspect(new BeforeAspect());
    }
}

class TargetClass {
    public function targetMethod() {
        echo "Target method executed\n";
    }
}

ApplicationAspectKernel::getInstance()->init([
    'debug' => true,
    'appDir' => __DIR__,
    'cacheDir' => __DIR__.'/cache'
]);

$target = new TargetClass();
$target->targetMethod();

以上方法根据复杂度需求可选择不同实现方案，从简单回调到专业 AOP 框架均可满足 before 事件的实现需求。