binding member functions in a variadic fashion

问题:

I have a member function with a variable number of parameters, stored in a std::function, and I want to bind the instance and get an independent function object.

template <class T, class R, class... Args>
void connect(const T& t, std::function<R(const T&, Args...)> f) {
  std::function<R(Args...)> = /* bind the instance c into the function? */
}

// ...

Class c;
connect(c, &Class::foo);

For a fixed number of arguments I'd use std::bind, but I don't see how to do this for variadic parameters.

回答1:

The solution is very simple, since you already have the amount of arguments and everything:

template <class T, class R, class... Args>
void connect(const T& t, std::function<R(const T&, Args...)> f) {
  // or capture 't' by-value
  std::function<R(Args...)> fun = [&t,f](Args... args){ f(t,args...); };
  // ...
}

Live example.