Use namespace in php

How can I use a namespace in PHP without doing a file include (laravel or synfony style)?

Example:

Change this code:     

  namespace fub;
  include 'file1.php';
  include 'file2.php';
  include 'file3.php';

  use foo as feline;
  use bar as canine;
  use other\animate; 

By this code:     

  namespace fub;

  use foo as feline;
  use bar as canine;
  use other\animate;