有没有一种方法可以根据子构造函数的参数值使用不同的参数调用父构造函数？

我有以下父类:

class Rectangle
{
public:
    Rectangle(std::string name, glm::vec3 top_left_corner, float height, float width, glm::vec3 color, bool fill);
    ~Rectangle();
    //...
}

还有子类:

class Wall :
    public Rectangle
{
public:
    Wall(std::string name, Position position, float scene_height, float scene_width, float thickness, glm::vec3 color);
    ~Wall();
    //...
}

其中 Position 是一个 enum ，它应该规定应该调用父构造函数的参数:

enum Position { UP, DOWN, LEFT, RIGHT };

所以基本上，我想在子构造函数中有这样的东西:

Wall::Wall(std::string name, Position position, float window_height, float window_width, float thickness, glm::vec3 color) {
    switch(position) {
    case UP:
        Rectangle(name, glm::vec3(0, window_height, 0), thickness, window_height, color, true);
        break;
    case DOWN:
        Rectangle(name, glm::vec3(0, thickness, 0), thickness, window_width, color, true);
        break;
    case LEFT:
        Rectangle(name, glm::vec3(0, window_height, 0), window_height, thickness, color, true);
        break;
    case RIGHT:
        Rectangle(name, glm::vec3(0, window_width - thickness, window_height), window_height, thickness, color, true);
        break;
    }
}

但是如你所知，我必须先调用父构造函数，例如:

Wall::Wall(std::string name, Position position, float window_height, float window_width, float thickness, glm::vec3 color)
    : Rectangle(name, glm::vec3(0, window_width - thickness, window_height), window_height, thickness, color, true) {}

这并没有给我太多回旋余地。什么是好的、面向对象的方法？

最佳答案

创建工厂方法:

Rectangle MakeRectangle(const std::string& name,
                        const Position& position,
                        float window_height, float window_width,
                        float thickness,
                        const glm::vec3& color)
{
    switch(position) {
    case UP:
        return Rectangle(name,
                         glm::vec3(0, window_height, 0),
                         thickness,
                         window_height,
                         color,
                         true);
    case DOWN:
        return Rectangle(name,
                         glm::vec3(0, thickness, 0),
                         thickness,
                         window_width,
                         color,
                         true);
    case LEFT:
        return Rectangle(name,
                         glm::vec3(0, window_height, 0),
                         window_height,
                         thickness,
                         color,
                         true);
    case RIGHT:
        return Rectangle(name,
                         glm::vec3(0, window_width - thickness,  window_height),
                         window_height,
                         thickness,
                         color,
                         true);
    }
    throw std::runtime_error("Invalid position");
}

然后

Wall::Wall(std::string name,
           Position position,
           float window_height, float window_width,
           float thickness,
           glm::vec3 color)
: Rectangle(MakeRectangle(name, position, window_height, window_width, thickness, color)){
// ...
}

关于c++ - 根据子构造函数参数调用具有不同参数的父构造函数，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/53031443/