Closure::bind (native JS-like bind in PHP)

bind-with-php.php

<?php

class A {
    public $param = 7;
}

class B {
    private $param = 28;
}

class C {
    public function __get($key)
    {
        if ($key === 'param') {
            return '42';
        }
        return 'Huh?';
    }
}

// An anoymous function using `$this`
$closure = function () { return $this->param; };

// Bind to an instance of A. Since param on A is public we don't
// need to change the scope
$aClosure = Closure::bind($closure, new A);
echo $aClosure() . PHP_EOL;

// Same as above but param on B is private so we need to change
// the scope to 'B'
$aClosure = Closure::bind($closure, new B, 'B');
echo $aClosure(). PHP_EOL;

// Save as A but with __get magic method
$aClosure = Closure::bind($closure, new C);
echo $aClosure(). PHP_EOL;

There is a non-static version called Closure::bindTo()