PHP additional parameters to usort

Question

The following code lays within a function which itself lays within a class. Its purpose is to avoid having one sorting function per $filter value :

$GLOBAL['filter'] = $filter;
usort($this->data, function($arr1, $arr2) {
    return ($arr1[$GLOBALS['filter']] > $arr2[$GLOBALS['filter']]) ? 1 : -1;
});

My solution works perfectly fine, but I find it rather inelegant. Would somebody have an idea to acheive the same goal without resorting to the $GLOBALS variable ?

Thanks for your propositions

Answer 1

Since you're using an anonymous function, you can use it as a closure like this:

$filter = <whatever>;
usort($this->data, function($arr1, $arr2) use ($filter) {
    return ($arr1[$filter] > $arr2[$filter]) ? 1 : -1;
});