Re: [Boost-users] Help with custom smart pointer const correctness

15 Apr 2009


      On Wed, Apr 15, 2009 at 4:16 PM, Dominique Devienne  wrote:
...
From my very limited meta-programming experience, I'm guessing I need
to fix the current typedef shared_ptr ident_ptr; in
ObjectPtr to somehow use MPL to "return" shared_ptr<typename
T::ident_type const> given a const T, and shared_ptr<typename
T::ident_type> given a T, but I don't know how to do that yet.
If someone would be kind enough to point me in the right direction,
I'd appreciate. Thanks, --DD
I figured the following which seems to work fine.
Didn't think I could do it on my own in 15min, thus my post ;)  --DD

#include 
#include 
#include 

template <class T> class ObjectPtr {
public:
    typedef typename remove_const<T>::type object_type;
    typedef typename object_type::ident_type ident_type;
    typedef shared_ptr<
        typename mpl::if_c::type
    > ident_ptr;

public:
    ident_ptr ident() const { return ident_; }

private:
    ident_ptr ident_;
};