Pimpl成語與類成員變量一起使用

Question

實現此類的正確方法是什麼？

//Header 
#include <boost/shared_ptr.hh> 

class MyClass 
{ 
public: 

    static foo() 
    static foobar(); 

private: 
    class pimpl; 
    static boost::shared_ptr<pimpl> m_handle; 
    static bool initialized; 
}; 


//source 
namespace 
{ 
    bool init() 
    { 
    //... 
    // init() can't access m_handle, unless it is a friend of MyClass 
    // but that seems a bit "tacky", is there a better way? 
    } 
} 


class MyClass::pimpl 
{ 
    public: 
     ~pimpl(){} 
}  


bool MyClass::initialized = init(); 

MyClass::foo() 
{ 
    //... 
} 

MyClass::foobar() 
{ 
    //... 
} 

Answer 1

MyClass是一個單身人士 - 有人稱它爲一個榮耀的全球。一個經常被濫用的模式。使用私人構建函數和一個公共靜態訪問：

MyClass { 
     public: 
      static MyClass& Instance() { 
       static MyClass obj; 
       return obj; 
      } 
     // ... 
     private: 
      MyClass() : m_handle(pimpl()), initialized(true) {} 
     // ... 
};