title: Forward declare a standard container?
body: <p>Is it possible to forward declare an standard container in a header file?  For example, take the following code:</p>
  
  <pre><code>#include &lt;vector&gt;
  
  class Foo
  {
  private:
      std::vector&lt;int&gt; container_;
      ...
  };
  </code></pre>
  
  <p>I want to be able to do something like this:</p>
  
  <pre><code>namespace std
  {
      template &lt;typename T&gt; class vector;
  }
  
  class Foo
  {
  private:
      std::vector&lt;int&gt; container_;
      ...
  };
  </code></pre>
  
  <p>Can this be done?</p>