C++ Insights - tuple get

Source:

#include <iostream>

template<typename T, typename... Ts> 
struct tuple{
    T first_;
    tuple<Ts...> rest_;

tuple(T first, Ts... rest) : first_{first}, rest_{tuple<Ts...>(rest...)} {}
};

template<typename T>
struct tuple<T>{
    T first_;

tuple(T first) : first_(first) {}
};

template<int n, typename T, typename... Ts>
struct nth_type : nth_type<n-1,Ts...>{
};

template<typename T, typename... Ts>
struct nth_type<0,T,Ts...>{
    using value_type = T;
};

template<int n>
struct getter{
    template<typename... Ts>
    static typename nth_type<n, Ts...>::value_type&
    get(tuple<Ts...>& t){
        return getter<n-1>::get(t.rest_);
    }
};

template<>
struct getter<0>{
    template<typename T, typename... Ts>
    static T& get(tuple<T, Ts...>& t){
        return t.first_;
    }
};

template<int n, typename... Ts>
typename nth_type<n, Ts...>::value_type &
get(tuple<Ts...>& t){
    return getter<n>::get(t);
}

int main()
{
    tuple<char, int, double> three('a', 1, 3.14);
    get<2>(three);
    
    return 0;
}

Source:

Insight:

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