Operator overload and inheritance

默认, operator overload被继承时时隐藏的.

//------------------------------------------------------
class IComparor
{
public:
    virtual int operator()(int x, int y) = 0;
};
//------------------------------------------------------
class ComparorA : public IComparor
{
public:
    using IComparor::operator();
    int operator()(int x, int y)
    {
        return x < y ? -1
            : x > y ? 1
            : 0;
    }
};
//------------------------------------------------------
class ComparorB : public IComparor
{
public:
    using IComparor::operator();
    int operator()(int x, int y)
    {
        return x < y ? 100
            : x > y ? -100
            : 0;
    }
};
//------------------------------------------------------

使用:

IComparor* comparor = new ComparorB();
int r1 = comparor->operator()(5, 6);
int r2 = (*comparor)(5, 6);