Better PHP usort() - php

Question

I needed to merge and then sort two arrays with dissimilar data structures (can't be sorted in the MySQL query) but where both had a created_on field.
So I am using usort() with a custom function.
In my controller
usort(merged_array, 'sort_records');
In my helper functions
if(!function_exists('sort_records')){
function sort_records($a,$b){
if ( $a['created_at'] == $b['created_at'] )
return 0;
if ( $a['created_at'] < $b['created_at'] )
return -1;
return 1;
}
}
I would like to make this sort_records() function reusable. So I can use it with other arrays. Maybe something like..
function sort_records($a,$b,$index){
if ( $a[$index] == $b[$index] )
return 0;
if ( $a[$index] < $b[$index] )
return -1;
return 1;
Is this possible with usort() since when you call the function it does not take parameters at all? Is there another option?

Answer 1

You can create a class
class SortRecord
{
private $index;
public function __construct($index)
{
$this->index = $index;
}
public function sort_records($a, $b)
{
if ( $a[$this->index] == $b[$this->index] )
return 0;
if ( $a[$this->index] < $b[$this->index] )
return -1;
return 1;
}
}
then you can pass it to usort.
$obj = new SortRecord('created_at');
usort($merged_array, array($obj, 'sort_records'));

Answer 2

Put usort inside sort_records and use anonymous function, like so:
function sort_records(&$array,$index){
return usort($array, function ($a, $b) use ($index) {
if ( $a[$index] == $b[$index] )
return 0;
if ( $a[$index] < $b[$index] )
return -1;
return 1;
});
}
Then you can call it with whatever index you need
sort_records($array, 'created_at');

Answer 3

You could also use the use keyword on your usort, but you'd have to declare the inner function as anonymous :
function better_usort($array, $index) {
return usort($array, function($a, $b) use($index){
if ($a[$index] == $b[$index])
return 0;
if ($a[$index] < $b[$index])
return -1;
return 1;
});
}
And then you can call it with
better_usort($merged_array, 'created_at');