的result_of不工作對我來說

Question

#include <type_traits> 
using namespace std; 

struct asd{ 
    void f(); 
}; 

int f(); 

typedef typename result_of<decltype(f)>::type result_free; 
typedef typename result_of<decltype(&asd::f)>::type result_mem; 

兩個類型定義給出錯誤

In file included from ../main.cpp:1:0: 
/usr/include/c++/4.6/type_traits: In instantiation of ‘std::_Result_of_impl<false, false, int>’: 
/usr/include/c++/4.6/type_traits:1215:12: instantiated from ‘std::result_of<int()>’ 
../main.cpp:10:41: instantiated from here 
/usr/include/c++/4.6/type_traits:1192:9: error: ‘std::declval [with _Tp = int, typename std::add_rvalue_reference<_Tp>::type = int&&]()’ cannot be used as a function 
../main.cpp:10:43: error: invalid combination of multiple type-specifiers 
../main.cpp:10:59: error: invalid type in declaration before ‘;’ token 
../main.cpp:11:49: error: ‘type’ in ‘struct std::result_of<void (asd::*)()>’ does not name a type 
../main.cpp:11:64: error: invalid type in declaration before ‘;’ token 

Answer 1

的result_of爲result_of<Fn(ArgTypes...)>，不只是result_of<Fn>;

嘗試

typedef typename result_of<decltype(&f)()>::type result_free; 
typedef typename result_of<decltype(&asd::f)(asd)>::type result_mem;