[boost] Re: boost::noncopyable

From: Maxim Yegorushkin (e-maxim_at_[hidden])
Date: 2004-12-19 22:39:32

Dirk Gregorius wrote:

[]

> I saw some code that declared the copy operations private in the base  
> class.
>
> class Interface
> {
> public:
>     virtual void f() = 0;
>
> private:
>     Interface( const Interface& );
>     Interface& operator=( const Interface& );
> }
>
> So in order to gain maximum style and correctness points I need to make  
> both
> classes ( Interface and Implementation ) noncopyable?

Only a base class. This prevents a compiler from generating copy ctor and  
assignment in its successors.

> Why is this possible?

Because a compiler generates copy ctor and assignment when nothing  
prevents it.

> Does it make sense to dereference an interface?

It does make sense, since there can be functions taking an interface by  
reference. But dereferencing and assigning it does not.

> Interface* p1 = make_interface();
> Interface* p2 = make_interface();
>
> *p1 = *p2;
>
> Or does your example only work with auto/smart pointers?

For plain pointers also.

Some say noncopyable interfaces may save from errors, though making them  
noncopyable I've never encountered that kind of errors.

-- 
Maxim Yegorushkin