While this may seem obvious, user-defined array sorting functions ( uksort(), uasort(), usort() ) will *not* be called if the array does not have *at least two values in it*.
The following code:
<?php
function usortTest($a, $b) {
var_dump($a);
var_dump($b);
return -1;
}
$test = array('val1');
usort($test, "usortTest");
$test2 = array('val2', 'val3');
usort($test2, "usortTest");
?>
Will output:
string(4) "val3"
string(4) "val2"
The first array doesn't get sent to the function.
Please, under no circumstance, place any logic that modifies values, or applies non-sorting business logic in these functions as they will not always be executed.