building and accessing a list of types at compile time
A solution utilizing a common header, variadic templates and a macro:
// Header common.h
// A distinct Void type
struct Void {};
template <typename ...> struct concat;
template <template <typename ...> class List, typename T>
struct concat<List<Void>, T>
{
typedef List<T> type;
};
template <template <typename ...> class List, typename ...Types, typename T>
struct concat<List<Types...>, T>
{
typedef List<Types..., T> type;
};
template <typename...> struct TypeList {};
template <>
struct TypeList<Void> {};
typedef TypeList<Void> TypelistVoid;
#define TYPE_LIST TypelistVoid
// Header foo.h
#include <common.h>
class Foo { };
typedef typename concat<TYPE_LIST, Foo>::type TypeListFoo;
#undef TYPE_LIST
#define TYPE_LIST TypeListFoo
// Header bar.h
#include <common.h>
class Bar { };
typedef typename concat<TYPE_LIST, Bar>::type TypeListBar;
#undef TYPE_LIST
#define TYPE_LIST TypeListBar
// Header main.h
#include "foo.h"
#include "bar.h"
struct list_of_types {
typedef TYPE_LIST type;
};
// Or just typedef TYPE_LIST list_of_types;
// Test
#include <iostream>
#include <typeinfo>
template <template <typename ...> class List, typename T, typename ...Types>
void info();
template <typename T, typename ...Types>
inline void info(TypeList<T, Types...>) {
std::cout << typeid(T).name() << std::endl;
info(TypeList<Types...>());
}
template <typename T>
inline void info(TypeList<T>) {
std::cout << typeid(T).name() << std::endl;
}
int main() {
info(list_of_types::type());
return 0;
}