你如何制作异构 boost::map?
我想要一个具有同构键类型但具有异构数据类型的映射.
I want to have a map that has a homogeneous key type but heterogeneous data types.
我希望能够做一些类似(伪代码)的事情:
I want to be able to do something like (pseudo-code):
boost::map<std::string, magic_goes_here> m;
m.add<int>("a", 2);
m.add<std::string>("b", "black sheep");
int i = m.get<int>("a");
int j = m.get<int>("b"); // error!
我可以有一个指向基类的指针作为数据类型,但我宁愿没有.
I could have a pointer to a base class as the data type but would rather not.
我以前从未使用过 boost,但查看了fusion 库但不知道我需要做什么.
I've never used boost before but have looked at the fusion library but can't figure out what I need to do.
感谢您的帮助.
推荐答案
#include <map>
#include <string>
#include <iostream>
#include <boost/any.hpp>
int main()
{
try
{
std::map<std::string, boost::any> m;
m["a"] = 2;
m["b"] = static_cast<char const *>("black sheep");
int i = boost::any_cast<int>(m["a"]);
std::cout << "I(" << i << ")
";
int j = boost::any_cast<int>(m["b"]); // throws exception
std::cout << "J(" << j << ")
";
}
catch(...)
{
std::cout << "Exception
";
}
}
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