How do I use std::result_of on a non-static method?

Question

I had a browse through the question on std::result_of on SO, but couldn't find an answer to this question.

How do I deduce the return type of a non-static method using std::return_type without using decltype?

#include <utility>                                                                 
#include <memory>                                                                                                                                   
struct A                                                                           
{                                                                                  
    int a;                                                                         

    int fun() { return 0;}                                                         
};                                                                                 

int main()                                                                         
{                                                                                  
    std::result_of<A::fun(A)>::type x; // error, argument 1 is invalid           
    std::result_of<A::fun()>::type x; // error, cannot call member function A::fun() without object             
    return 0;                                                                      
}

I know I can use a combination of declval and decltype to get the same effect but I was wondering if I could achieve this using result_of directly?

@dolan yup that works, but it feels a bit like cheating! I was hoping for a solution without `decltype`. — quant, Sep 19 '14 at 02:53
`result_of` needs to be used with *types*. Good luck doing it without `decltype`. — T.C., Sep 19 '14 at 02:58
@BryanChen if there's no reason to avoid `decltype` then there's no reason to *use* `result_of`... — quant, Sep 19 '14 at 03:00
@quant ["`result_of` has an advantage that is backward-compatible"](http://stackoverflow.com/a/2689761/642626) — Bryan Chen, Sep 19 '14 at 03:03

How do I use std::result_of on a non-static method?

0 Answers0