如何从它的私有构造函数访问 class 的私有成员

Question

我有以下 class，这里我正在尝试从私有构造函数访问 class 的私有成员。

class House {
private:
    int len;
    int wid;
    House()
    {
    }
public:
    ~House() 
    {
        std::cout << "destructor call" << std::endl;
    }
    static std::shared_ptr<House> house;
    static auto getHouse(const int length, const int width);

    void setlen(int lenth) { len = lenth; }
    void setwid(int width) { wid = width; }
    int getlen() { return len; }
    int getwid() { return wid; }
};

auto House::getHouse(const int length, const int width)
 {
    House::house = std::make_shared<House>();
    if ((House::house->getlen()==length) && (House::house->getwid()== width)) 
    {
        return House::house;
    }
    else
    {
        House::house->setlen(length);
        House::house->setwid(width);

        return House::house;
    }
}

我收到以下错误消息

Severity Code Description Project File Line Suppression State Error C2248 'House::House': cannot access private member declared in class 'House' TestC++ c:\program files (x86)\microsoft visual studio17\community\vc\tools\msvc.14.26428\include\memory 1770

Answer 1

因为 House 没有 public 构造函数，class 之外的代码不允许构造 House。但你正试图做到这一点，在这里：

House::house = std::make_shared<House>();

std::make_shared的实现调用new构造一个新的House，但是std::make_shared无法访问House的私有构造函数。要修复它，您需要自己构建 House：

House::house.reset(new House);

如何从它的私有构造函数访问 class 的私有成员

How to access private members of a class from it's private constructor

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