improved SFINAE in type_caster_generic (closes #70)

This commit is contained in:
Wenzel Jakob 2016-01-18 21:00:25 +01:00
parent 92b2f452f0
commit 260bc58f57
2 changed files with 10 additions and 2 deletions

View File

@ -209,11 +209,11 @@ public:
operator type*() { return (type *) value; }
operator type&() { return *((type *) value); }
protected:
template <typename T = type, typename std::enable_if<std::is_copy_constructible<T>::value, int>::type = 0>
template <typename T = type, typename std::enable_if<detail::is_copy_constructible<T>::value, int>::type = 0>
static void *copy_constructor(const void *arg) {
return new type(*((const type *) arg));
}
template <typename T = type, typename std::enable_if<!std::is_copy_constructible<T>::value, int>::type = 0>
template <typename T = type, typename std::enable_if<!detail::is_copy_constructible<T>::value, int>::type = 0>
static void *copy_constructor(const void *) { return nullptr; }
};

View File

@ -240,6 +240,14 @@ template <typename T> struct intrinsic_type<T&&> { typedef type
template <typename T, size_t N> struct intrinsic_type<const T[N]> { typedef typename intrinsic_type<T>::type type; };
template <typename T, size_t N> struct intrinsic_type<T[N]> { typedef typename intrinsic_type<T>::type type; };
/** \brief SFINAE helper class to check if a copy constructor is usable (in contrast to
* std::is_copy_constructible, this class also checks if the 'new' operator is accessible */
template <typename T> struct is_copy_constructible {
template <typename T2> static std::true_type test(decltype(new T2(std::declval<T2>())) *);
template <typename T2> static std::false_type test(...);
static const bool value = std::is_same<std::true_type, decltype(test<T>(nullptr))>::value;
};
/// Helper type to replace 'void' in some expressions
struct void_type { };