title: -Wunused-variable warning
body: <p>I am implementing the singleton design pattern in a school assignment, and this is my class header file:</p>
  
  <pre><code>class Scheduler {
  public:
      static Scheduler * instance();
      ~Scheduler();
  
  private:
      Scheduler();
  };
  
  static Scheduler * _singleton = 0; // WARNING HERE
  </code></pre>
  
  <p>My problem is that I keep getting this error:</p>
  
  <pre><code>../Scheduler.h:60:20: warning: ‘_singleton’ defined but not used [-Wunused-variable]
  </code></pre>
  
  <p>And we have to submit assignments with no compilation warnings. How do I get rid of this warning? There's no need for me to use <code>_singleton</code> in the header file itself so I'm not sure what to do. I know it's stupid, but still...</p>
  
  <p>Ideas?</p>