title: C++ 2D shared_ptr array initialize with abstract polymorphic type
body: <p>I have Polymorphic type that i need to initialize 2D array 
  is like shared_ptr** Map</p>
  
  <p>this is my initializer when there wasnt shared_ptr, can you tell me the solution to work ? 
  Error is incompatible pointer types shared_ptr** and Game_Object***</p>
  
  <pre><code>Map = new shared_ptr&lt;Game_Object&gt;();
      for (int i = 0; i &lt; (int) width_; i++)
          Map[i] = new shared_ptr&lt;Game_Object&gt;();
  </code></pre>
  
  <p><code>Map = new shared_ptr&lt;Game_Object&gt;();</code> is <code>shared_ptr&lt;Game_Object&gt;*</code> 
  and i need to get this "<code>shared_ptr&lt;Game_Object&gt;**</code>" how i do that?</p>