variadic-templates

I need a way to pass a variable amount of parameters to a function in this circumstance: template<typename ...T> struct Lunch { Lunch(T...){} }; template<typename T> T CheckLuaValue(lua_State* luaState,int index) { //Do Stuff return value; } template <class MemberType, typename ReturnType, typename... Params> struct MemberFunctionWrapper <ReturnType (MemberType::*) (Params...)> { static int CFunctionWrapper (lua_State* luaState) { ReturnType (MemberType::*)(Params...) functionPointer = GetFunctionPointer(); MemberType* member = GetMemberPointer(); int index = 1; //Get a value for each type in

I want to be able to call a function with a template parameter that is of function type (including parameter and return types), i.e. double(int, long) , and in the function separate the types and use them individually. For example I want to be able to call a function printRes<double(int, long)>(); This function above should parse the template argument and extract the return type double and output it. I know how to do this using a class and variadic templates: #include <iostream> #include <typeinfo> template <typename T> class A {}; template <typename Res, typename... Args> class A<Res (Args...

While answering this question I wrote this working code, wrapping function passed in template arguments: template<typename Fn, Fn fn, typename... Args> auto wrapper(Args... args)->decltype(fn(args...)){ return fn(args...); } #define WRAPPER(FUNC) wrapper<decltype(&FUNC), &FUNC> Example usage (I use this code for testing): int min(int a, int b){ return (a<b)?a:b; } #include<iostream> using std::cout; int main(){ cout<<WRAPPER(min)(10, 20)<<'\n'; } Two people told me to use perfect forwarding . When I asked how to do this, one of them redirected me here . I read question, carefully read best

I am trying to forward some arguments to do inplace construction of objects . I don't quite get the rationale behind the usage of emplace in associative containers or may be I am just using/thinking in a wrong way. It would be great if someone can share code snippets for usage. Associative container like map always store an object of kind pair() , and the emplace function says that it will call the constructor of the object stored (which for is always pair in case of maps) by forwarding the arguments. So are we just restricted to provide two arguments (key , value) even if the the function has

I'm trying to understand the compiler error that I'm getting fo the code below. I've got a variadic template function which accepts a lambda with the specified types, and attempting to call that function results in the template not being considered a valid candidate due to a mismatch. #include <functional> template<typename ... ResultTypes> void executeWithResultHandler(std::function<void (ResultTypes...)> lambda) { } int main(int argc, char **argv) { executeWithResultHandler<int>([] (int arg) { }); return 0; } This results in the following error: $ c++ -std=c++11 reduction.cpp reduction.cpp

I have this sample code, which do what I need for a 3-parameter function : template<typename T>T GETPARAM(void) { return T(); } template<>int GETPARAM(void) { return 123; } template<>double GETPARAM(void) { return 1.2345; } template<>const char *GETPARAM(void) { return "hello"; } template<typename P1, typename P2, typename P3, typename RES> RES BuildArgs3(RES(*fn)(P1, P2, P3)) { P1 p1 = GETPARAM<P1>(); P2 p2 = GETPARAM<P2>(); P3 p3 = GETPARAM<P3>(); return fn(p1, p2, p3); } int print3(int a, double b, const char *c) { Cout() << "Print3:" << a << ", " << b << ", " << c << "\n"; return 1; } main

When running this: template <typename T> struct CodeByType { static const int32_t Value = 7; }; template <> struct CodeByType<int> { static const int32_t Value = 1; }; template <typename Arg, typename... Args> int32_t Sum() { // The compiler complains on this line return Sum<Arg>() + Sum<Args...>(); } template <typename Arg> int32_t Sum() { return CodeByType<Arg>::Value; } int main() { auto sum = Sum<int, char, double>(); } I'm getting: Error C2668 'Sum': ambiguous call to overloaded function Can someone please explain why and how to overcome it? This looks awfully similar to the below code,