[Boost-users] Using Adaptable Generator concept with generate_n and boost smart pointers

Subject: [Boost-users] Using Adaptable Generator concept with generate_n and boost smart pointers
From: Marco Craveiro (marco.craveiro_at_[hidden])
Date: 2012-10-18 19:43:11

Hi boosters,

I'm trying to create a class that models the concept of adaptable
generator [1]. The idea is that it generates pointers to test data
objects which I'd like to then put inside of smart pointers such as
shared_ptr or scoped_ptr (or even std::shared_ptr) via generate_n,
etc. This is a (non-compilable) example of my intentions:

#include <algorithm>
#include <iostream>
#include <memory>
#include <vector>
#include <iterator>

struct base { int i; };
struct derived : public base { int z; };

struct generator
{
    typedef base result_type;
    result_type* operator()() {
        return new derived();
    }
};

int main(void) {
    std::vector<std::shared_ptr<base> > z;
    std::generate_n(std::back_inserter(z), 5, generator());
    return 0;
}

The std::shared_ptr is incidental; it could have been
boost::shared_ptr, etc - its up to client code to decide. I get this
to work fine when result_type is say boost::shared_ptr<base> but what
I really like is for it to be a raw pointer; is there some boost magic
(or standard C++ 11 magic) I can apply to convert it to the value_type
of the container I'm trying to generate?

Many thanks for your time,

Marco
-- 
So young, and already so unknown -- Pauli
blog: http://mcraveiro.blogspot.com
[1] http://www.sgi.com/tech/stl/AdaptableGenerator.html