#include <boost/shared_ptr.hpp>
#include <boost/enable_shared_from_this.hpp>
#include <iostream>

struct X: public boost::enable_shared_from_this<X>
{};

void null_deleter(const void *)
{}

template<typename T, typename U>
bool are_shared_owners(const boost::shared_ptr<T> &a, const boost::shared_ptr<U> &b)
{
    return a && !(a < b) && !(b < a);
}

int main()
{
    boost::shared_ptr<X> px(new X);
    boost::shared_ptr<X> first_sft = px->shared_from_this();
    boost::shared_ptr<X> px2(px.get(), &null_deleter);
    boost::shared_ptr<X> second_sft = px->shared_from_this();
    std::cout << "are_shared_owners = " << are_shared_owners(first_sft, second_sft) << std::endl;
    return 0;
}