define a closure as method from class

Question

i\'m trying to play with php5.3 and closure.

I see here (Listing 7. Closure inside an object : http://www.ibm.com/developerworks/opensource/library/os-php-5.3new2/in

Answer 1

Well, the whole reason that you can't use $this, is because the closure is an object in the background (the Closure class).

There are two ways around this. First, is add the __invoke method (What's called if you call $obj())..

class Dog {

    public function __invoke($method) {
        $args = func_get_args();
        array_shift($args); //get rid of the method name
        if (is_callable(array($this, $method))) {
            return call_user_func_array(array($this, $method), $args);
        } else {
            throw new BadMethodCallException('Unknown method: '.$method);
        }
    }

    public function greet($greeting) {
        $self = $this;
        return function() use ($greeting, $self) {
            $self('do_greet', $greeting);
        };
    }

    protected function do_greet($greeting) {
        echo "$greeting, I am a {$this->_color} dog named {$this->_name}.";
    }
}

If you want the closure to not change if you modify the host object, you can just change the return function to something like:

public function greet($greeting) {
    $self = (clone) $this;
    return function() use ($greeting, $self) {
        $self('do_greet', $greeting);
    };
}

The other option, is to provide a generic getter:

class Dog {

    public function __get($name) {
        return isset($this->$name) ? $this->$name : null;
    }

}

For more information, see: http://www.php.net/manual/en/language.oop5.magic.php