title: Redefining constants in PHP
body: <p>Is it possible to redefine a constant in php which was defined by the <code>define</code> function? 
  I have a class with several constants that contains the user data. I'm trying to use the class for more than one user.</p>
  
  <pre><code>define('ALLEGRO_ID', 'id');
  define('ALLEGRO_LOGIN', 'login');
  define('ALLEGRO_PASSWORD', 'passwd');
  define('ALLEGRO_KEY', 'key');
  define('ALLEGRO_COUNTRY', 123);
  
  $allegro = new AllegroWebAPI( );                
  $allegro -&gt; Login();
  </code></pre>
  
  <p>I did not write this class, but I am using it due to time constraints. I do not know why the creator of this class <code>defined</code> the user data rather than using the variables in the instance.</p>
  
  <p>I know that constants should be constant (obviously!), but I'm looking for a trick to redefine them.</p>