#include <type_traits>
#include <iostream>

template <bool Mode>
class Foo
{   
    public:

        template <bool M = Mode, typename std::enable_if<M>::type* = nullptr>
        void bar()
        {
            std::cout << "true" << std::endl;
        }

        template <bool M = Mode, typename std::enable_if<!M>::type* = nullptr>
        void bar()
        {
            std::cout << "false" << std::endl;
        }
};

int main()
{
    Foo<false> f;
    
    f.bar();
}