Question

is any way to return reference at class parameter or global variable? I try this

class test{

  public static $var;

  public static function get(&$ref){

    $ref = self::$var;

  }

}

test::get($ref);
$ref = 'test';
var_dump(test::$var);

it’s a basic example, i know, then this example can be use another way, but i need to keep principle

---

this is my function, where is problem with reference to variable

class mySession{

    public static function issetKeys(){

      $keys = func_get_args();

      $session = &$_SESSION;
      $c = 0;

      if (is_array($keys)){
        foreach ($keys as $val){

          if (isset($session[$val])){
            $session = &$session[$val];
            $c++;
          }
          else break;

        }
      }

      return $c == count($keys);

    }

    public static function &get(){

      $keys = func_get_args();

      $session = &$_SESSION;

      if (is_array($keys)){
        foreach ($keys as $val){

          if (!isset($session[$val])) $session[$val] = Array();
          $session = &$session[$val];

        }
      }

      return $session;

    }

  }

  function getValue(){

    if (!mySession::issetKeys('p1', 'p2')){
      $session = mySession::get('p1', 'p2');
      $session = 'string';
    }

    return mySession::get('p1', 'p2');

  }

  print_r($_SESSION);

but no variable save in to $_SESSION

Answer 1

In the general case, a parameter only exists for the duration of the function to which it was passed; when the function returns, the call stack is unwound and the parameter disappears, which means that any reference to a variable that lived in the call stack will no longer be valid (since it points to memory which has been freed and now quite possibly contains something else entirely.)

That said, it is possible to return a reference to a parameter, although this will not work if you try to return a reference to a variable that actually lives in the stack (that is, one that was not passed by reference):

$myGlobal = 10;

// Note the & before the function name
function &returnReference(&$x) {
    return $x;
}

// Note the & before the function call
$someValue = &derp($myGlobal);
echo $myGlobal;

$someValue = 0;
echo $myGlobal;