title: operator +' : redefinition; different type modifiers
body: <p>I have the code:</p>
  
  <pre><code>// class declaration
  class Vector3D;
  
  // class declaration and definition
  class Point3D { 
      // ...
  
      // function declaration (only needs class declarations)
      Point3D operator+(const Vector3D &amp;);
  };
  
  // class definition
  class Vector3D {
      // ...
  };
  
  // function definition (needs class definitions)
  inline Point3D Point3D::operator+(const Vector3D &amp;vector) {
      // ...
  }
  </code></pre>
  
  <p>But I get errror:
  <em>'Graphic::Point3D::operator +' : redefinition; different type modifiers</em></p>