我如何使一个类的接口匹配两倍,但在哪些模板上可以专门化?

不能从本机类型派生。改为使用合成:

#include <cstdlib>
#include <string>
#include <stdexcept>
#include <iostream>
using namespace std;

template<typename Type = double, const Type& Min = -10.0, const Type& Max = 10.0> class Bounded
{
public:
    Bounded() {};
    Bounded(const Type& rhs) : val_(rhs) 
    { 
        if(rhs > Max || rhs < Min) 
            throw logic_error("Out Of Bounds"); 
    }

    operator Type () const 
    { 
        return val_; 
    }

    Type val_;
};


int main()
{
    typedef Bounded<double, -10.0, 10.0> double_10;
    double_10 d(-4.2);
    cout << "d = " << d << "\n";
    double d_prime = d;
    cout << "d_prime = " << d_prime << "\n";
    double_10 d2(-42.0);
    cout << "d2 = " << d << "\n";


    return 0;
}

输出是:

d = -4.2
d_prime = -4.2