PHP callback - how to execute it in a class?

Question

I'm trying to understand the popular use of PHP closure/ callback of functions in routing requests within modern frameworks. Slim for example, allows you to do the following:

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

My experiment:

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();

How can execute the callback in the class so it return Hello World?

felipsmartins · Accepted Answer · 2015-10-04 14:41:24Z

1

When designing frameworks it's a bit more complex in order to get better flexibility.
But on this simple case you simply could use call_user_func_array() or call_user_func(). I adivise to use call_user_func_array() because it's easier when passing many args:

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();

edited Oct 4, 2015 at 14:41

answered Oct 4, 2015 at 5:32

felipsmartins

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Comments

Aggie · Accepted Answer · 2015-10-04 05:45:59Z

1

Based on your sample code, it should be like this:

    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'

answered Oct 4, 2015 at 5:45

Aggie

1394 bronze badges

2 Comments

Aggie Over a year ago

Sorry, i didn't see @elipsmartins answer when posting -- its not yet there when i'm writing. Our answer actually same. I'm still new in Stackoverflow.

Run Over a year ago

No worries. It helps too! ;)

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