#include <iostream>
using namespace std;
 
template <typename T>
class DoubleBuffer {
public:
    using value_type = T;
    using reference = T&;
    using const_reference = T const &;
    using const_type = const T;
    using pointer = T*;
    //...
};
 
int main() {
    int dummy;
    DoubleBuffer<int>::value_type vt = dummy;
    DoubleBuffer<int>::reference ref = dummy;
    DoubleBuffer<int>::const_reference cref = dummy;
    DoubleBuffer<int>::const_type ct = 12345;
    DoubleBuffer<int>::pointer p = &dummy;
 
	return 0;
}

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