返回 - 方法链接

<?php
class DB {

  private $query = 'some query';

  public function get()
  {
    return $this;
  }

  public function query()
  {
    // do the query function
  }

  public function __toString()
  {
     return $this->query;
  }
}

$db = new DB;
echo $db->get(); //prints 'some query'
$db->get()->query(); // runs the query() method

$db->get()->query()

$somevar = $db->get();
$somevar->query();