PHP 回调 - 如何在类中执行它？

Question

我试图了解在现代框架中路由请求时 PHP 闭包/函数回调的流行用法。例如，Slim 允许您执行以下操作：

$app->get('/hello/:name', function ($name) {
    echo "Hello, $name";
});
$app->run();

我的实验：

class Foo
{
    private $string;
    private $callback;

    public function get($string, $callback)
    {
        $this->string = $string;
        $this->callback = $callback;
    }

    public function run()
    {
        return $this->get($this->string, $this->callback);
    }
}

$Foo = new Foo;
$Foo->get('/world', function($name) {
    return "Hello " . $name;
});

$Foo->run();

如何在类中执行回调，使其返回Hello World？

Answer 1

在设计框架时，它会稍微复杂一些，以便获得更好的灵活性。
但在这个简单的案例中，您只需使用call_user_func_array() 或call_user_func()。我建议使用call_user_func_array()，因为它在传递许多参数时更容易：

class Foo
{
    private $string;
    private $callback;

    public function get($string, callable $callback)
    {
        $this->string = $string;
        $this->callback = $callback;
    }

    public function run()
    {
         return call_user_func_array($this->callback, [$this->string]);
        # OR 
        # return call_user_func($this->callback, $this->string);
        # OR
        #$fn = $this->callback; return $fn($this->string);

    }
}

$Foo = new Foo;
$Foo->get('/world', function($name) {
    return "Hello " . $name;
});

print $Foo->run();

Answer 2

根据您的示例代码，应该是这样的：

    public function get($string, $callback)
    {
        //assign input parameter to object's propety
        $this->string = $string;
        $this->callback = $callback;

    }

    public function run()
    {
        /* if you want to avoid using this variable
           use call_user_func */
        $callback = $this->callback;

        // run the callback
        return $callback($this->string);
    }
}

$Foo = new Foo;
$Foo->get('world', function($name) {
    return "Hello " . $name;
});

$return = $Foo->run();
var_dump($return); //this will return 'Hello world'