c – 调用函数并传递存储在元组中的参数？

> Pass tuple’s content as variadic function arguments
> How do I expand a tuple into variadic template function’s arguments?

并且,根据答案,提出了这个代码：

#include <functional>

template < int N,typename... ARGS >
struct apply_func {
   static void applyTuple( std::function<void(ARGS...)>& f,const std::tuple<ARGS...>& t,ARGS... args ) {
    apply_func<N-1>::applyTuple( f,t,std::get<N-1>( t ),args... );
  }
};

template <typename... ARGS>
struct apply_func<0,ARGS...>
{
  static void applyTuple( std::function<void(ARGS...)>& f,const std::tuple<ARGS...>& /* t */,ARGS... args ) {
    f( args... );
  }
};

template < typename... ARGS >
void applyTuple( std::function<void(ARGS...)>& f,std::tuple<ARGS...> const& t ) {
   apply_func<sizeof...(ARGS),ARGS...>::applyTuple( f,t );
}

template<typename... ARGS>
class Foo
{
    std::function<void(ARGS...)> m_f;
    std::tuple<ARGS...> *argument_pack;

    public:
    Foo(std::function<void(ARGS...)> f):m_f(f){}
    void operator()(ARGS... args);
    void run();

};

template<typename... ARGS>
void Foo<ARGS...>::operator()(ARGS... args)
{
    m_f(args...); // this works
}

template<typename... ARGS>
void Foo<ARGS...>::run()
{
    applyTuple<ARGS...>(m_f,*argument_pack); // this doesn't compile
}

void bar(int i,double d){}

int main(void)
{
    Foo<int,double> foo(bar);
    foo(1,1.0); // this works
    foo.run(); // this doesn't compile
}

如果使用’g -std = c 0x’进行编译,则最后一行的下一行将显示以下错误：

test.cc: In function ‘void applyTuple(std::function<void(ARGS ...)>&,const std::tuple<_Elements ...>&) [with ARGS = {int,double}]’:
test.cc:52:9:   instantiated from ‘void Foo<ARGS>::run() [with ARGS = {int,double}]’
test.cc:61:17:   instantiated from here
test.cc:27:8: error: no matching function for call to ‘apply_func<2,int,double>::applyTuple(std::function<void(int,double)>&,const std::tuple<int,double>&)’
test.cc:27:8: note: candidate is:
test.cc:6:19: note: static void apply_func<N,ARGS>::applyTuple(std::function<void(ARGS ...)>&,const std::tuple<_Elements ...>&,ARGS ...) [with int N = 2,ARGS = {int,double}]
test.cc:6:19: note:   candidate expects 4 arguments,2 provided
test.cc: In static member function ‘static void apply_func<N,double}]’:
test.cc:27:8:   instantiated from ‘void applyTuple(std::function<void(ARGS ...)>&,double}]’
test.cc:52:9:   instantiated from ‘void Foo<ARGS>::run() [with ARGS = {int,double}]’
test.cc:61:17:   instantiated from here
test.cc:9:9: error: no matching function for call to ‘apply_func<1>::applyTuple(std::function<void(int,double>&,const double&,int&,double&)’
test.cc:9:9: note: candidate is:
test.cc:6:19: note: static void apply_func<N,ARGS ...) [with int N = 1,ARGS = {}]
test.cc:6:19: note:   candidate expects 2 arguments,5 provided
test.cc: In static member function ‘static void apply_func<N,ARGS = {}]’:
test.cc:9:9:   instantiated from ‘static void apply_func<N,double}]’
test.cc:27:8:   instantiated from ‘void applyTuple(std::function<void(ARGS ...)>&,double}]’
test.cc:61:17:   instantiated from here
test.cc:9:9: error: no matching function for call to ‘get(const std::tuple<>&)’
test.cc:9:9: note: candidates are:
/usr/include/c++/4.6/utility:133:5: note: template<long unsigned int _Int,class _Tp1,class _Tp2> typename std::tuple_element<_Int,std::pair<_Tp1,_Tp2> >::type& std::get(std::pair<_Tp1,_Tp2>&)
/usr/include/c++/4.6/utility:138:5: note: template<long unsigned int _Int,class _Tp2> const typename std::tuple_element<_Int,_Tp2> >::type& std::get(const std::pair<_Tp1,_Tp2>&)
/usr/include/c++/4.6/tuple:531:5: note: template<long unsigned int __i,class ... _Elements> typename std::__add_ref<typename std::tuple_element<__i,std::tuple<_Elements ...> >::type>::type std::get(std::tuple<_Elements ...>&)
/usr/include/c++/4.6/tuple:538:5: note: template<long unsigned int __i,class ... _Elements> typename std::__add_c_ref<typename std::tuple_element<__i,std::tuple<_Elements ...> >::type>::type std::get(const std::tuple<_Elements ...>&)

我错过了什么？谢谢！