[Boost-users] [scoped_ptr] Transferring pointers to scoped_ptr member

From: Christian Larsen (contact_at_[hidden])
Date: 2008-08-17 14:41:42

Hi,

This is just make sure I'm not being too careful in this situation. So 
please confirm whether this is correct.

I have a class with two scoped_ptr members, and I want to pass two 
pointers to the constructor, which will then transfer the ownership of 
both to the two member scoped_ptrs. I assume the following is not safe:

(I didn't try compiling; using namespace boost and std.)

     struct B {};

     class A
     {
     public:
         A(B* b1, B* b2)
             : b1_(b1), b2_(b2)
         {}
     private:
         scoped_ptr<B> b1_;
         scoped_ptr<B> b2_;
     };

     // Create an A this way:
     A a(new B, new B);

Is it correct that this could fail if one of the 'new B's throw, thus 
leaking before the constructor ever started?

If that is so, is this then the correct way to achieve the same in a 
safe manner?

     struct B {};

     class A
     {
     public:
         A(auto_ptr<B>& b1, auto_ptr<B>& b2)
             : b1_(b1.release()), b2_(b2.release())
         {}
     private:
         scoped_ptr<B> b1_;
         scoped_ptr<B> b2_;
     };

     // Create an A this way:
     A a(auto_ptr<B>(new B), auto_ptr<B>(new B));

Best regards,
Christian