php - Accessing private variables from within a closure

Question

I'm trying to reference a private variable of an object from within a closure. The code below would seem to work, but it complains Fatal error: Cannot access self:: when no class scope is active in test.php on line 12 and Fatal error: Using $this when not in object context in test.php on line 20.

Any ideas how to accomplish the same results using a closure while keeping the variables private and without making helper functions (defeating the whole idea of a private variable).

class MyClass
{

    static private $_var1;
    private $_var2;

    static function setVar1( $value )
    {
        $closure = function () use ( $value ) {
            self::$_var1 = $value;
        };
        $closure();
    }

    function setVar2( $value )
    {
        $closure = function () use ( $value ) {
            $this->_var2 = $value;
        };
        $closure();
    }

}

MyClass::setVar1( "hello" ); //doesn't work

$myclass = new MyClass;
$myclass->setVar2( "hello" ); //doesn't work

Answer 1

Edit to note, this answer was originally meant for PHP5.3 and earlier, it's possible now. For current information, see this answer.

---

This is not directly possible. In particularly, closures have no associated scope, so they cannot access private and protected members.

You can, however, use references:

<?php
class MyClass
{

    static private $_var1;
    private $_var2;

    static function setVar1( $value )
    {
        $field =& self::$_var1;
        $closure = function () use ( $value,  &$field ) {
            $field = $value;
        };
        $closure();
    }

    function setVar2( $value )
    {
        $field =& $this->_var2;
        $closure = function () use ( $value, &$field ) {
            $field = $value;
        };
        $closure();
    }

}

MyClass::setVar1( "hello" );

$myclass = new MyClass;
$myclass->setVar2( "hello" );