Simple logger for PHP

TrackerPDO.php

<?php 
class TrackerPDO {
  private static $_instance = null;
  
  private static $request_log = array();

  private function __construct() {
  }

  protected function __clone() {
  }
  
  static public function getInstance() {
    if(is_null(self::$_instance)) self::$_instance = new self();
    return self::$_instance;
  }

  public function log($entry) {
    self::$request_log[] = $entry;
  }

  public function getLog() {
    return self::$request_log;
  }
}