title: Codeigniter: Remove a URI segment on specific controller
body: <p>I have a controller named <code>cart</code> with many functions.</p>
  
  <p>I need ONLY for this specific controller, to "redirect" the second segment to another one, specifically:</p>
  
  <p><code>http://www.domain.com/cart/music</code> should show the <code>cart/show/music</code> function.</p>
  
  <p>I tried doing:</p>
  
  <pre><code>class Cart extends MY_Controller {
  
      public function show(){
          $routes['cart/musica'] = 'cart/show/$1';
          //More code...
      }
  
  } 
  </code></pre>
  
  <p>This is what I saw on other answers but can't make it work and actually doesn't seem right to me.</p>
  
  <p>This 'redirect' should only be valid for some of the functions in <code>Cart class</code>.
  How can this be handled?</p>