type_traits
1544 ワード
#include
namespace namespace269 {
/** 2 , , , , */
struct __true_type { };
struct __false_type { };
template
struct __type_traits {
typedef __true_type this_dummy_member_must_be_first;
typedef __false_type has_trivial_default_constructor;
typedef __false_type has_trivial_copy_constructor;
typedef __false_type has_trivial_assignment_operator;
typedef __false_type has_trivial_destructor;
typedef __false_type is_POD_type;
};
}
template
void test_tpye_traits(T& t, namespace269::__true_type) {
std::cout << "true" << std::endl;
}
template
void test_tpye_traits(T& t, namespace269::__false_type) {
std::cout << "false" << std::endl;
}
template
void test_tpye_traits(T& t) {
typedef typename namespace269::__type_traits::is_POD_type is_POD_type;
test_tpye_traits(t, typename namespace269::__type_traits::is_POD_type());
}
class A {
public:
};
class B {
};
namespace namespace269 {
template <>
struct __type_traits{
typedef __true_type is_POD_type;
};
template <>
struct __type_traits {
typedef __false_type is_POD_type;
};
}
int main(void) {
A a;
B b;
test_tpye_traits(a); // true
test_tpye_traits(b); // false
return 0;
}