Re: New Singleton Scheme

What about this implementation:

class Singleton
    {
    public:
       static Singleton *instance();
    private:
       Singleton() { }

       static volatile bool mInitialized;
       static Singleton *mInstance;
    };

volatile bool Singleton::mInitialized = false;
Singleton *Singleton::mInstance = 0;

Singleton *Singleton::instance()
    {
    if (not mInitialized)
       {
       /* scope */
          {
          Lock lock;
          if (mInstance == 0)
             {
             mInstance = new Singleton;
             }
          }
       mInitialized = true;
       }

    return mInstance;
    }

Precisely it is not double check, that's the idea. The scope is
probably not necessary - it causes, that lock will be released before
setting mInitialized - another "sequence point" added. Also mInstance
is not declared as volatile, because protected by Lock.

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