to_tuple.py

#!/usr/bin/env python3

print('''
#pragma once
#include <type_traits>
#include <tuple>

// Converts POD struct to std::tuple

// Autogenerated by totuple.py

// Adapted from https://www.reddit.com/r/cpp/comments/4yp7fv/c17_structured_bindings_convert_struct_to_a_tuple/

template <class T, class... TArgs> decltype(void(T{std::declval<TArgs>()...}), std::true_type{}) test_is_braces_constructible(int);
template <class, class...> std::false_type test_is_braces_constructible(...);
template <class T, class... TArgs> using is_braces_constructible = decltype(test_is_braces_constructible<T, TArgs...>(0));

struct any_type {
    template<class T> constexpr operator T(); // non explicit
};

template<class T> auto to_tuple(T&& object) noexcept {
    using type = std::decay_t<T>;
''')

elems = 20

for i in range(elems, 1, -1):
    print("    %s if constexpr(is_braces_constructible<type, %s>{}) {" % ('' if i == elems else 'else', ', '.join(['any_type' for x in range(1,i)])))
    plist = ', '.join(['p%d' % x for x in range(1,i)])
    print("        auto&& [%s] = object;" % plist)
    print("        return std::make_tuple(%s);" % plist)
    print("    }")
print("    else { return std::make_tuple(); }")
print("}")