关于wikibook上的singleton的疑问

这个是wikibook中关于Design Pattern的内容，我觉得还蛮好的

https://en.wikibooks.org/wiki/C%2B%2B_Programming/Code/Design_Patterns#Behavioral_Patterns

但是遇到个问题。

关于Singleton

下面给出的这个demo我觉得是错的（或者我没理解好，我错了 : )

class StringSingleton
 {
 public:
     // Some accessor functions for the class, itself
     std::string GetString() const 
     {return mString;}
     void SetString(const std::string &newStr)
     {mString = newStr;}

     // The magic function, which allows access to the class from anywhere
     // To get the value of the instance of the class, call:
     //     StringSingleton::Instance().GetString();
     static StringSingleton &Instance()
     {
         // This line only runs once, thus creating the only instance in existence
         static StringSingleton *instance = new StringSingleton;
         // dereferencing the variable here, saves the caller from having to use 
         // the arrow operator, and removes temptation to try and delete the 
         // returned instance.
         return *instance; // always returns the same instance
     }

 private: 
     // We need to make some given functions private to finish the definition of the singleton
     StringSingleton(){} // default constructor available only to members or friends of this class

     // Note that the next two functions are not given bodies, thus any attempt 
     // to call them implicitly will return as compiler errors. This prevents 
     // accidental copying of the only instance of the class.
     StringSingleton(const StringSingleton &old); // disallow copy constructor
     const StringSingleton &operator=(const StringSingleton &old); //disallow assignment operator

     // Note that although this should be allowed, 
     // some compilers may not implement private destructors
     // This prevents others from deleting our one single instance, which was otherwise created on the heap
     ~StringSingleton(){} 
 private: // private data for an instance of this class
     std::string mString;
 };

是我中二了。。。无视这个blog提出的问题 :D