Re: [Boost-users] noncopyable

Subject: Re: [Boost-users] noncopyable
From: Joe Gottman (jgottman_at_[hidden])
Date: 2008-12-04 20:14:10

Hicham Mouline wrote:
> Like this?
> 
> class C : public boost::noncopyable {
> public:
>   ... clone() const
>   {
>    ...
>   }
> private:
>    C( const C& rhs )
>    {
>      ....
>    }
> };
> 
> ... instance c1 of C exists here ....
> 
> What possible return types of clone() const are possible?
> .A native reference
> .An auto_ptr
> 
> 
> To be honest, I'm not sure myself of how it would be used...
>

   In my experience, the major reason for a clone() function is to allow 
"virtual copy constructors".

struct Base
{
    virtual Base *clone() const = 0;
//You might return auto_pointer<Base> or shared_ptr<Base> instead
};

struct Derived1 : public Base
{
    Base *clone() const {return new Derived1();}
};

struct Derived2: public Base
{
     Base *clone() const {return new Derived2();}
};