title: PHP invisible class properties
body: <p>Ok I know I can have private properties which prevent a property from being used outside of the class, but is it possible to also make that property invisible outside of the class?</p>
  
  <p>What I mean is, is it possible to make a way so that the property doesn't even show up if I do a <code>print_r()</code> or <code>foreach()</code> of the class?</p>