c++ - Boost::list_of 无法对稍微复杂的数据结构进行模板推导

Question

我必须使用跨平台代码。现在，我一直在使用 VS2012，它不支持 C++11 统一初始化。所以，我正在使用 boost::list_of。

对于简单的情况，这是可行的。但是，对于稍微复杂的数据结构，这似乎行不通。

#include <iostream>
#include <boost/assign.hpp>
#include <boost/assign/list_of.hpp>
#include <tuple>
using namespace std;
using namespace boost::assign;

int main() {

class NodeInfo
{
    public:
        NodeInfo (int Parent, int childLeft, int childRight) :
            m_parent (Parent), m_childLeft(childLeft), m_childRight(childRight)
            {   

            }
        private:
            int m_parent;
            int m_childLeft;
            int m_childRight;
};
typedef std::vector<NodeInfo> MyData1;
MyData1 expData =  list_of(NodeInfo(1,2,3)) (NodeInfo(3,4,5));

typedef std::tuple<int , std::vector<NodeInfo>> MyData2;
MyData2 expData21 =  std::make_tuple(10 , expData);

 // I would have really liked the following:
 // error:
 MyData2 expData22 =  std::make_tuple(10 , list_of(NodeInfo(1,2,3) (NodeInfo(3,4,5) )));

//error:From the example in boost doc, this should work. 
MyData2 expData3 =  list_of<MyData2> (std::make_tuple(10 , expData));

MyData2 expData4;
// error: Most probably need to write my own list_inserter for MyTest,
// after turning MyTest into a class. 
// I really don't want to go this route, if the other options are at all 
// possible. Why extend the boost library, if it's at all possible ? 
insert( expData4 )
    ( std::make_tuple(10 , expData) )( std::make_tuple(20 , expData) ); 

return 0;
}

我在这里添加了部分代码。 https://ideone.com/kIYDu0

Answer 1

确实，使这项工作顺利进行的最佳方法是扩展库(或者编写您自己的辅助函数)。

但是，您尝试的东西从来都不是功能。 documentation显示如何将 list_of 分配给 vector :

Tuple mytuple2 = std::make_tuple(10, 
        list_of(NodeInfo(1, 2, 3))(NodeInfo(3, 4, 5)).to_container(std::get<1>(mytuple2))
    );

更多注意事项:

• 在我看来，您忘记了将 expData3 和 expData4 设为容器。
• 在某些时候，您使用 std::make_tuple(1,2,3) 作为 NodeInfo。我不明白那应该如何运作

这是包含修复/解决方法的完整列表:

Live On Coliru

#include <iostream>
#include <boost/assign.hpp>
#include <boost/assign/list_of.hpp>
#include <tuple>
using namespace std;
using namespace boost::assign;

int main() {

    class NodeInfo {
      public:
        NodeInfo(int Parent, int childLeft, int childRight)
                : m_parent(Parent), m_childLeft(childLeft), m_childRight(childRight) {}

      private:
        int m_parent;
        int m_childLeft;
        int m_childRight;
    };

    typedef std::vector<NodeInfo> NodeInfos;
    NodeInfo node1(1,2,3), node2(3,4,5);
    NodeInfos infos = list_of(node1)(node2);

    typedef std::tuple<int, std::vector<NodeInfo> > Tuple;
    Tuple mytuple = std::make_tuple(10, infos);

    // I would have really liked the following:
    Tuple mytuple2 = std::make_tuple(10, 
            list_of(NodeInfo(1, 2, 3))(NodeInfo(3, 4, 5)).to_container(std::get<1>(mytuple2))
        );

    std::vector<Tuple> 
        mytuples = list_of<Tuple>(std::make_tuple(10, infos)),
        mytuples2;

    //// still figuring this out:
    // insert(mytuples2)(Tuple(10, infos))(Tuple(20, infos));
}