Examples/test-suite/cpp11_result_of.i

/* This testcase checks whether SWIG correctly uses the new result_of class
   and its templating capabilities introduced in C++11. */
%module cpp11_result_of

%inline %{
#include <functional>
typedef double(*fn_ptr)(double);
%}

namespace std {
  // Forward declaration of result_of
  template<typename Func> struct result_of;
  // Add in the required partial specialization of result_of
  template<> struct result_of< fn_ptr(double) > {
    typedef double type;
  };
}

%template() std::result_of< fn_ptr(double) >;

%inline %{

double square(double x) {
  return (x * x);
}

template<class Fun, class Arg>
typename std::result_of<Fun(Arg)>::type test_result_impl(Fun fun, Arg arg) {
  return fun(arg);
}

std::result_of< fn_ptr(double) >::type test_result_alternative1(double(*fun)(double), double arg) {
  return fun(arg);
}
%}

%{
// Another alternative approach using decltype (not very SWIG friendly)
std::result_of< decltype(square)&(double) >::type test_result_alternative2(double(*fun)(double), double arg) {
  return fun(arg);
}
%}

%inline %{
#include <iostream>

void cpp_testing() {
  std::cout << "result: " << test_result_impl(square, 3) << std::endl;
  std::cout << "result: " << test_result_impl<double(*)(double), double>(square, 4) << std::endl;
  std::cout << "result: " << test_result_impl< fn_ptr, double >(square, 5) << std::endl;
  std::cout << "result: " << test_result_alternative1(square, 6) << std::endl;
  std::cout << "result: " << test_result_alternative2(square, 7) << std::endl;
}
%}

%template(test_result) test_result_impl< fn_ptr, double>;
%constant double (*SQUARE)(double) = square;