boost-variant

When trying to parse text into a boost::variant, the variant's value does not get changed. The parsers by themselves appear to work fine, so my assumption is that I'm doing something wrong with the variant code. I'm using boost 1.46.1 and the following code compiles in Visual Studio 2008. 1st Update hkaiser noted that the rule and grammar template arguments must not be Variant but Variant() . This got a bit "further" as I now have a compilation error in boost_1_46_1\boost\variant\variant.hpp(1304) . The comment says: // NOTE TO USER : // Compile error here indicates that the given type is not

GOAL: I would like to achieve type-safe dynamic polymorphism (i.e. run-time dispatch of a function call) on unrelated types - i.e. on types which do not have a common base class . It seems to me that this is achievable, or at least theoretically sound. I will try to define my problem more formally. PROBLEM DEFINITION: Given the following: two or more unrelated types A1, ..., An , each of which has a method called f , possibly with different signatures, but with the same return type R ; and a boost::variant<A1*, ..., An*> object v (or whatever other type of variant) which can and must assume at

I'm having trouble choosing between Boost.Any and Boost.Variant. When should I use each one? What are the advantages and disadvantages of each? I am basically looking to store some states from external sources. drby Have you looked at the comparison in the variant library already? (Not sure what states from external sources are, so it's kind of hard to say what's more appropriate for you.) 来源： https://stackoverflow.com/questions/1366524/boost-any-vs-boost-variant

I look at this grate code based on boost.Any and cant help but wonder if we could use Boost.Variant instead. I wonder if such API would be possible: void voidFunc() { std::cout << "void called" << std::endl; } int stringFunc(std::string str) { std::cout << str << std::endl; return 0; } int main() { some_map_like_type<std::string, boost::variant> funcs; funcs.insert<void , void >("voidFunc", &voidFunc)); // now our variant vould contain something like boost::function<void, void> funcs.insert<int , std::string>("stringFunc", &stringFunc)); // and now we added to our variant a new type: boost:

I am trying to escape a string in quotation marks using boost::spirit::karma. This works fine if it's just a string. However, for a string in a boost::variant in a std::vector, it does not. Just printing the string does work however, I do not quite understand why. Line (1) works fine, but doesn't do what I want. Line (2) should do it, but doesn't. #include <iostream> #include <string> #include <boost/variant.hpp> #include <boost/spirit/include/karma.hpp> namespace karma = boost::spirit::karma; typedef std::vector<boost::variant<int, std::string>> ParameterList; typedef boost::variant<int, std:

As I understood all types of boost.variant are parsed into real types (meaning as if boost variant<int, string> a; a="bla-bla" would after compilation turn into string a; a="bla-bla" ) And so I wonder: how to get what type was put into boost variant? What have I tried: #include <boost/variant.hpp> #include <boost/function.hpp> #include <boost/shared_ptr.hpp> #include <iostream> int main() { typedef boost::function<double (double x)> func0; typedef boost::function<double (double x, double y)> func1; typedef boost::variant<int, func0, func1> variant_func; func1 fn = std::plus<double>(); variant