如何在C ++中创建Comparable接口并传递一系列可比对象？

可运行的代码示例：在此处在线运行此代码

我确实知道正确的完整示例应该使用模板类，但是为了简单起见，我希望看到一个没有模板的幼稚实现。

我还知道，<或>运算符的虚拟运算符重载在C ++中比多态的compareTo（）方法签名更合适。

我也知道数组不是协变的，也不是协变的，我还是想看看这个例子在C ++中应该如何工作，我不想使用像vector这样的STL模板类型

我定义了抽象类（接口）：

class Comparable {
    public:
    virtual int compareTo(Comparable *) = 0;
};

我有一个基类，与“可比”的概念无关

class Shape {
protected:    
    int width, height;
public:
    Shape(int a = 0, int b = 0)
    {
        width = a;
        height = b;
    }
    virtual int area() = 0;
};

我定义了一个形状后代矩形，它想成为一个可比较的：

class Rectangle : public Shape, public Comparable {

public:
    Rectangle(int a = 0, int b = 0) : Shape(a, b) {}

    virtual int compareTo(Comparable * other){
        return height - dynamic_cast<Rectangle *>(other)->height;
    } 

    int area()
    {
        return (width * height);
    }
};

测试方法和主程序：请参见test（...）方法中的注释。我在这里想念什么？

void test(Comparable* items[]){
    // tests polymorphic behavior. For example this would be a sort algorithm, 
    // which gets and array of comparables (array of pointers to Comparable)
    
    int result = items[0]->compareTo(items[1]);

    // result is 42 here, despite it is the meaning of life, is not appropriate. It is the area() method return value of items[0], instead of compareTo()
    // Debugging justifies, that not the compareTo method is called on the items[0] instance
    // instead the area() method... something is wrong with the cast... and not the correct method address used from the vtable ...
}

int main()
{
    Rectangle a(3,14), b(3,11);
    Rectangle* rectangles[2];
    rectangles[0] = &a;
    rectangles[1] = &b;

    // This is not good, but what would be the correct?
    test((Comparable **)rectangles);

    return 0;
}