title: PHP class_alias returns error
body: <p>I just wanted to create an alias for my database class using the following code:</p>
  
  <pre><code> &lt;?php
  class MySqlDatabase extends engine{
  class_alias ('MySqlDatabase','Db');
  
  public static $connection;
  // etc.
  }
  ?&gt;
  </code></pre>
  
  <p>When I run the code in PHP 5.6.19 I get the following error:</p>
  
  <blockquote>
    <p>Parse error: syntax error, unexpected 'class_alias' (T_STRING), expecting function (T_FUNCTION) in /(somedir)/dbconnect.php on line 18</p>
  </blockquote>
  
  <p>Am I doing something wrong here?
  According the the PHP manual the function is available on PHP 5 >= 5.3.0 - PHP 7</p>