Re: [Boost-users] Returning a shared_ptr or raw pointer from a template function

Subject: Re: [Boost-users] Returning a shared_ptr or raw pointer from a template function
From: Steven Watanabe (watanabesj_at_[hidden])
Date: 2009-03-30 23:18:52

AMDG

Ryan McConnehey wrote:
> I would like to have a class that has this create function and upon 
> creation of the class specify if the create function returns a raw 
> pointer or shared_ptr.
>
> template <class U>  //The U specifies is the create function returns a 
> raw or shared pointer
> class Rdi
> {
> template <class S>
> U create(void)
> {
>   U temp(new S());
>   return temp;
> }
> };
>
> How would I modify this class to allow the user to make the following 
> calls?
>
> Rdi<boost::shared_ptr> fun1;

This won't compile because boost::shared_ptr is a class template.

> Tm* tm3 = fun1.create<Tm>();
>
> Rdi<raw Pointer???> fun2;
> boost::shared_ptr<Tm> tm4 = fun2.create<Tm>();
>
> Any help would be appreciated.

Try

#include <boost/mpl/apply.hpp>
#include <boost/type_traits/add_pointer.hpp>
#include <boost/shared_ptr.hpp>

template<class U>
class Rdi {
    typedef typename boost::mpl::apply<U, Rdi>::type ptr_type;
    template<class S>
    ptr_type create();
};

Rdi<boost::shared_ptr<boost::mpl::_1> > fun1;
Rdi<boost::add_pointer<boost::mpl::_1> > fun2;

In Christ,
Steven Watanabe