[Boost-users] multi_index_container with protected constructor

17 Jul 2013

      Hi,

I want to use boost::multi_index_container with a class that have
protected constructors, but the compile fails.
I think I should make multi_index_container a friend of my class, but I
don't know how.

#include <iostream>
#include <boost/shared_ptr.hpp>
#include <boost/multi_index_container.hpp>
#include <boost/multi_index/ordered_index.hpp>
#include <boost/multi_index/composite_key.hpp>
#include <boost/multi_index/mem_fun.hpp>

class Item
{
public:
	typedef boost::shared_ptr<Item> P;

	static P create()
	{
		return P(new Item());
	}
	static P create(P item)
	{
		return P(new Item(item));
	}

protected:
	Item()
	{
	}

	Item(P item)
	: source(item->get_source())
	, target(item->get_target())
	{
	}

public:
	std::string source;
	std::string target;

	std::string get_source() const {return source;}
	std::string get_target() const {return target;} 

	struct key : boost::multi_index::composite_key<
		P,
		boost::multi_index::const_mem_fun<Item, std::string,
&Item::get_source>,
		boost::multi_index::const_mem_fun<Item, std::string,
&Item::get_target> 
		>{};

	typedef boost::multi_index_container<
		P,
		boost::multi_index::indexed_by<
			boost::multi_index::ordered_non_unique<
				key,
				boost::multi_index::composite_key_result_less<key::result_type>
				>
			>
	> index_t;
};

int main()
{
	Item::index_t index;

	Item::P t1 = Item::create();

	index.insert(t1);

	return 0;
}

Thanks in advance:
Imre Horvath

[Boost-users] multi_index_container with protected constructor

Horváth Imre