[boost] shared_ptr rebind

From: Ben Young (ben.young_at_[hidden])
Date: 2003-03-31 05:35:39

Hi,

I was wondering whether anyone had thought about adding a rebind nested
template class to the boost ptrs, similar to those used by allocators.
A situation has recently occurred where I need to get a ptr to a derived
class from a pre to a base class, where the ptr to the base class is used
a typedef e.g

struct Base {};

typedef boost::shared_ptr<Base> BasePtr;

void func(const BasePtr& base)
{

}

struct Derived : public Base {};

typedef boost::shared_ptr<Derived> DerivedPtr;
        ^^^^^^^^^^^^^^^^^^^^^^^^^^
        Don't want to have to do this

func(DerivedPtr(new Derived)) ....... etc

The reason I dont want to have to do the second typedef is that we have a
number of smart pointer classes of our own, and the type of the BasePtr
should be an implementation detail. If boost::shared_ptr had a rebind,
then we could add it to our own classes as well, and the actual wrapper
used would become an implementation detail

Cheers

Ben Young