array_reduce to use dynamic variables pass in second function - php

Question

I have below $test array
Array
(
[0] => Array
(
[quantity] => 3
[stock_id] => _PHONE
)
[1] => Array
(
[quantity] => 3
[stock_id] => 102
)
[2] => Array
(
[quantity] => 4
[stock_id] => _PHONE
)
[3] => Array
(
[quantity] => 3
[stock_id] => 102
)
[4] => Array
(
[quantity] => 4
[stock_id] => _PHONE
)
[5] => Array
(
[quantity] => 6
[stock_id] => _PHONE
)
[6] => Array
(
[quantity] => 2
[stock_id] => 102
)
)
and to sum same stock_id keys to one, i use below functions:
function sum($array, $key){
isset($array[$key['stock_id']]) ? $array[$key['stock_id']]['quantity'] += $key['quantity'] : $array[$key['stock_id']] = $key;
return $array;
};
//merge same stock_id and sum the quantity same stock id
$sum_same_stock_id = array_reduce($test, "sum");
and the result went well like below:
$sum_same_stock_id:
Array
(
[_PHONE] => Array
(
[quantity] => 17
[stock_id] => _PHONE
)
[102] => Array
(
[quantity] => 8
[stock_id] => 102
)
)
So the question here is, I wanted to pass an dynamic keys values not just fixed values stock_id & quantity in sum function above. Have tried variety ways but still can't figured out the way. And can we put those functions into class as well?
Any advise is appreciated!

Answer 1

Maybe you can use the "use" function for the callback?
See https://www.php.net/manual/en/functions.anonymous.php