Sort array by object property in PHP?

Question

If I have an object as such:

class Person {
  var $age;
  function __construct($age) {
    $this->age = $age;
  }
}

and I have any array

Answer 1

If all member variables in question are guaranteed to be different, it will be simpler and faster to create a new collection indexed by these values and then ksort it:

 foreach($obj_list as $obj)
    $map[$obj->some_var] = $obj;
 ksort($map);
 /// $map now contains the sorted list

If there are duplicate values, you can still avoid usort by utilizing a less known feature of sort that arrays of arrays are sorted by the value of the first scalar member.

 foreach($obj_list as $obj)
    $map[] = array($obj->some_var, $obj);
 sort($map); // sorts $map by the value of ->some_var

I guess this still will be 10000000 times faster than usort