title: Access to class which is only in cpp file of parent
body: <p>I want to call a class which is only in the file of a parent source class file. In fact I have 3 classes in 4 files: </p>
  
  <pre><code>parent.h 
  parent.cpp 
  child.h
  child.cpp
  </code></pre>
  
  <p>The "main" classes are <code>Child</code> and <code>Parent</code>. The class <code>Otherclass</code> is in the parent.h file above the definition of the <code>Parent</code> class.</p>
  
  <p>How can I get access to the class <code>Otherclass</code> which is only in the parent.cpp file in the child.cpp file?</p>
  
  <p>(Unfortunately I'm not allowed to make big changes in the parent files.)</p>
  
  <p>parent.cpp:</p>
  
  <pre><code>using ParentNamespace::Parent;
  
  
  namespace other
  {
      class Otherclass
      {
      public:
          Otherclass()
          {
              // do something
          }
  
          ~Otherclass()
          {
          }
      };
  }
  
  
  Parent::Parent()...
  ...
  // here the Parent class continues normal
  </code></pre>
  
  <p>child.cpp:</p>
  
  <pre><code>#include "parent.h"
  
  Child::Child() :
  ParentNamespace::Parent()
  ...
  ...
  ...
      // here I want to use Otherclass
  </code></pre>