最近看了C++11的一些特性，最感兴趣的是可变模板参数，自动类型推断和匿名函数。
Loki中的TypeList，是需要递归定义的，并且需要一个NullType作为尾节点。
可变模板参数使得实现TypeList更简洁，更易懂。
以下是我用C++11实现TypeList。
////////////////////////////////////////////////////////// template<typename... TList> struct typelist { }; typedef typelist<> nulllist; ////////////////////////////////////////////////////////// template<typename... TList> struct length; template<typename... TList> struct length< typelist<TList...> > { enum { value = sizeof...(TList) }; }; ////////////////////////////////////////////////////////// template<typename T, typename... TList> struct push_front; template<typename T, typename... TList> struct push_front< T, typelist<TList...> > { typedef typelist<T, TList...> type; }; ////////////////////////////////////////////////////////// template<typename... TList> struct pop_front; template<typename T, typename... TList> struct pop_front< typelist<T, TList...> > { typedef typelist<TList...> type; }; template<> struct pop_front< nulllist > { typedef nulllist type; }; ////////////////////////////////////////////////////////// template<unsigned int N, typename... TList> struct at; template<unsigned int N, typename T, typename... TList> struct at< N, typelist<T, TList...> > { typedef typename at< N-1, typelist<TList...> >::type type; }; template<typename T, typename... TList> struct at< 0, typelist<T, TList...> > { typedef T type; }; template<> struct at< 0, nulllist > { typedef nulllist type; }; ////////////////////////////////////////////////////////// template<int A, int B> struct IndexFixer { enum { value = (A == B) ? B : A + 1 }; }; ////////////////////////////////////////////////////////// template<typename T, typename... TList> struct indexof; template<typename T, typename H, typename... TList> struct indexof< T, typelist<H, TList...> > { enum { value = IndexFixer<indexof<T, typelist<TList...>>::value, -1>::value }; }; template<typename T, typename... TList> struct indexof< T, typelist<T, TList...> > { enum { value = 0 }; }; template<typename T> struct indexof< T, nulllist > { enum { value = -1 }; }; ////////////////////////////////////////////////////////// template<typename A, typename B> struct concat; template<typename... A, typename... B> struct concat<typelist<A...>, typelist<B...> > { typedef typelist<A..., B...> type; }; template<typename T, typename... TList> struct concat<typelist<TList...>, T > { typedef typelist<TList..., T> type; }; template<typename T, typename... TList> struct concat< T, typelist<TList...> > { typedef typelist<T, TList...> type; }; ////////////////////////////////////////////////////////// template<typename T, typename... TList> struct erase; template<typename T, typename H, typename... TList> struct erase<T, typelist<H, TList...> > { typedef typename concat<H, typename erase< T, typelist<TList...> >::type>::type type; }; template<typename T, typename... TList> struct erase<T, typelist<T, TList...> > { typedef typelist<TList...> type; }; template<typename T> struct erase<T, nulllist > { typedef nulllist type; }; ////////////////////////////////////////////////////////// template<typename T, typename... TList> struct erase_all; template<typename T, typename H, typename... TList> struct erase_all<T, typelist<H, TList...> > { typedef typename concat<H, typename erase_all< T, typelist<TList...> >::type>::type type; }; template<typename T, typename... TList> struct erase_all<T, typelist<T, TList...> > { typedef erase_all< T,typelist<TList...> > type; }; template<typename T, typename U> struct erase_all<T, typelist<U> > { typedef U type; }; template<typename T> struct erase_all<T, nulllist > { typedef nulllist type; }; ////////////////////////////////////////////////////////// template<typename T, typename...TList> struct no_duplicate; template<typename T, typename...TList> struct no_duplicate< typelist<T, TList...> > { private: typedef typename no_duplicate< typelist<TList...> >::type inner; typedef typename erase<T, inner>::type inner_result; public: typedef typename concat<T, inner_result>::type type; }; template<> struct no_duplicate< nulllist > { typedef nulllist type; }; ////////////////////////////////////////////////////////// template<typename R, typename T, typename...TList> struct replace; template<typename R, typename T, typename H, typename...TList> struct replace<R, T, typelist<H, TList...> > { typedef typename concat<H, typename replace<R, T, typelist<TList...>>::type>::type type; }; template<typename R, typename H, typename...TList> struct replace<R, H, typelist<H, TList...> > { typedef typename concat<R, typelist<TList...> >::type type; }; template<typename R, typename T> struct replace<R, T, nulllist > { typedef nulllist type; }; ////////////////////////////////////////////////////////// template<typename R, typename T, typename...TList> struct replace_all; template<typename R, typename T, typename H, typename...TList> struct replace_all<R, T, typelist<H, TList...> > { typedef typename concat<H, typename replace_all<R, T, typelist<TList...>>::type>::type type; }; template<typename R, typename H, typename...TList> struct replace_all<R, H, typelist<H, TList...> > { typedef typename concat<R, typename replace_all<R, H, typelist<TList...>>::type >::type type; }; template<typename R, typename T> struct replace_all<R, T, nulllist > { typedef nulllist type; }; ////////////////////////////////////////////////////////// template<typename T, typename...TList> struct reverse; template<typename T, typename...TList> struct reverse<typelist<T, TList...> > { typedef typename concat<typename reverse<typelist<TList...>>::type, T>::type type; }; template<> struct reverse< nulllist > { typedef nulllist type; };