sort by field use class

SortHelper.php

<?php
class SortHelper {
  private static $field;
  static  function byField(&$data, $field) {
    self::$field = $field;
    return usort($data, array('self', 'cmp'));
  }
  private static function cmp($a, $b) {
    return $a[self::$field] > $b[self::$field];
  }
}

//example
$data = array(array('t'=>1, 'p'=>'aBc'), array('t'=>3, 'p'=>'aBb'));

$rzt = SortHelper::byField($data, 't');
var_dump($data, $rzt);

对比使用闭包的实现方式：https://gist.github.com/brothertao/d9de53cb43752f38a6cf

线程不安全，闭包是线程安全的