对boost.fusion矢量中元素的引用

Question

编辑-请忽略-这个问题围绕一个简单的打字错误解决了。我需要休息一下

如何访问助推融合矢量元素的引用？

与boost.tuples的tuples::get<i>(variable)（返回引用）不同，fusion::at_c<i>(variable)返回常量，这给我带来了困难。

下面说明了我的问题

#include <iostream>
#include <boost/tuple/tuple.hpp> 
#include <boost/fusion/include/vector.hpp>
#include <boost/fusion/include/at.hpp>
using namespace boost;
int
main  (int ac, char **av)
{
   fusion::vector<int, char, std::string> vec(1, 'x', "howdy");
   tuples::tuple <int, char, std::string> tup(1, 'x', "howdy");
   std::cout<< fusion::at_c<0>(vec)<<std::endl;  //outputs 1
   std::cout<< tuples::get<0> (tup) <<std::endl; //outputs 1
   //fusion::at<0>(vec) = 2; //doesn't compile
   tuples::get<0>(tup) = 2;    //works fine
   std::cout<< fusion::at_c<0>(vec) <<std::endl; //can't make this output 2.
   std::cout<< tuples::get<0> (tup) <<std::endl; //outputs 2
}

Answer 1

你就不能做fusion::at_c<0>(vec) = 2;吗？