Object factory using Boost.Phoenix, Boost.Function and Boost.SmartPtr libraries

factory.cpp

#include <boost/foreach.hpp>
#include <boost/function.hpp>
#include <boost/spirit/include/phoenix.hpp>
#include <boost/shared_ptr.hpp>
#include <iostream>
#include <map>
#include <string>
#include <vector>

struct Parent { virtual std::string hello() const = 0; };
struct Object1 : Parent { std::string hello() const { return "Hi, Object1"; } };
struct Object2 : Parent { std::string hello() const { return "Ay, Object2"; } };

struct bad_type_exception : std::exception {
    char const * what() const throw() { return "No such class!"; }
};

typedef boost::shared_ptr<Parent> ParentPtr;

struct Factory {
    typedef std::map<std::string, boost::function<ParentPtr()> > FactoryMap;
    FactoryMap f;
    Factory() {
        using boost::phoenix::new_;
        using boost::phoenix::construct;
        f["Object1"] = construct<ParentPtr>(new_<Object1>());
        f["Object2"] = construct<ParentPtr>(new_<Object2>());
        // ...
    }
    ParentPtr operator()(std::string const & type) const {
        FactoryMap::const_iterator it = f.find(type);
        if (it == f.end()) throw bad_type_exception();
        return it->second();
    }
};

int main() {
    Factory factory;
    std::vector<std::string> types;
    types.push_back("Object1");
    types.push_back("Object2");
    std::vector<ParentPtr> items;
    BOOST_FOREACH(std::string const & type, types)
        items.push_back(factory(type));
    BOOST_FOREACH(ParentPtr item, items)
        std::cout << item->hello() << std::endl;
    // Prints:
    //  Hi, Object1
    //  Ay, Object2
}