c++ - 如何检查参数包中的每种类型是否唯一？

Question

<分区>

Answer 1

你可以这样做:

#include <type_traits>

template <class ... Trest>
struct unique_types;

template <class T1, class T2, class ... Trest>
struct unique_types<T1, T2, Trest ...>
 : unique_types<T1, T2>, unique_types<T1, Trest ...>, unique_types<T2, Trest ...> {};

template <class T1, class T2>
struct unique_types<T1, T2>
{
    static_assert(!std::is_same<T1, T2>::value, "Types must be unique");
};

int main()
{
    // OK.
    unique_types<int, double, char, float> foo;

    // Should not compile.
    unique_types<int, double, char, double> bar;
}