[boost] Re: boost::noncopyable

From: Maxim Yegorushkin (e-maxim_at_[hidden])
Date: 2004-12-19 06:53:34

Dirk Gregorius wrote:

> Does inheriting from boost::noncopyable has the same effect like making  
> the copy c'tor and the assignment operator private without implementing  
> them? The authors of the smart_ptr library suggest the following for the  
> use of the smart pointers with interfaces:
>
> class Interface
> {
> public:
>     virtual void f() = 0;
>     virtual void g() = 0;
>
> protected:
>     ~Interface( void )  {};  // non-virtual
> }
>
> // #1
> class Implementation : public Interface
> {
> public:
>     void f() { /* Implementation */ }
>     void g() { /* Implementation */ }
>
> private:
>     // Not to be implemented
>     Implementation( const Implementation& );
>     Implementation& operator=( const Implementation& );
> };

Does it really make any sense making only implementation noncopyable,  
rather than interface? If you deal with interfaces only it won't save you  
 from errors like this:

     std::auto_ptr<Interface> create() { return  
std::auto_ptr<Interface>(new Implementation); }

     void foo()
     {
         std::auto_ptr<Interface> a(create()), b(create());

         *a = *b; // oops, no error here, Implementation::operator= is not  
considered
     }

-- 
Maxim Yegorushkin