title: PHP Root namespace
body: <p>I have got a single file in which I need specify classes in multiple namespaces, something like:</p>
  
  <pre><code>&lt;?php
  
  namespace library;
  
  class ClassInLib {
     ...
  }
  
  namespace \; //Switch to root namespace
  
  class ClassInRoot {
     ...
  }
  </code></pre>
  
  <p>The above code has a syntax error at <code>namespace \;</code>. How can I switch from the <code>library</code> namespace to the root namespace?</p>
  
  <p>Why do I need this: I need to mock a bunch of classes during unit testing and I don't think these very short mock classes justify being in separate files.</p>