Availability of method vars within a sub-function - php

Question

Referencing a method parameter variable from within a sub-function of that method doesn't seem to work even when global is specified.
public function sortArray(&$array, $keyToCompare){// BOOL sortArray( ARR &$array, STR $keyToCompare )
function cmpVals($pairA, $pairB){
global $keyToCompare;
return strcmp($pairA[$keyToCompare], $pairB[$keyToCompare]);
}
return uasort($array, 'cmpVals');
}
Is it even possible to reference a method parameter from within a sub-function? If so... how?
For my specific example above I realise I could use a closure to achieve the same goal but I don't want the script to be PHP 5.3 dependent.

Answer 1

Any reason you can't make it static?
class YourClassName {
public static $keyToCompare;
public function sortArray(&$array, $keyToCompare){// BOOL sortArray( ARR &$array, STR $keyToCompare )
self::$keyToCompare = $keyToCompare;
function cmpVals($pairA, $pairB){
$keyToCompare = YourClassName::$keyToCompare;
return strcmp($pairA[$keyToCompare], $pairB[$keyToCompare]);
}
return uasort($array, 'cmpVals');
}
}

Answer 2

You seemed to be already using OOP in PHP 5.3. Might as well create a sorter class?
class Sorter{
private $key;
function __construct($key){
$this->key = $key;
}
private function compare($a, $b){
return strcmp($a[$this->key], $b[$this->key]);
}
public function sort($a){
uasort($a, array($this, 'compare'));
}
}

Answer 3

Another option is an anonymous function:
public function sortArray(&$array, $keyToCompare){
return uasort($array, function($pairA, $pairB) uses ($keyToCompare) {
return strcmp($pairA[$keyToCompare], $pairB[$keyToCompare]);
});
}
Untested, on a train :D, but see the documentation for more info.
FYI, the pass by reference is unnecessary since you don't modify the array.. PHP won't make a copy so there is no memory issues passing by value.