Qt “vùng riêng tư:” đây là gì?

Tôi hiểu cách sử dụng nó, nhưng cú pháp của nó làm tôi khó chịu. "Vùng riêng tư:" đang làm gì?

Tôi chưa bao giờ thấy điều gì đó giữa từ khóa private và: trong định nghĩa lớp trước đây. Có một số phép thuật C ++ ưa thích đang diễn ra ở đây không?

Và ví dụ ở đây:

 #include <QObject>

 class Counter : public QObject
 {
     Q_OBJECT

 public:
     Counter() { m_value = 0; }

     int value() const { return m_value; }

 public slots:
     void setValue(int value);

 ...

Slots are a Qt-specific extension of C++. It only compiles after sending the code through Qt's preprocessor, the Meta-Object Compiler (moc). See http://doc.qt.io/qt-5/moc.html for documentation.

Edit: As Frank points out, moc is only required for linking. The extra keywords are #defined away with the standard preprocessor.

The keywords such as public, private are ignored for Qt slots. All slots are actually public and can be connected

Declaring slots as private means that you won't be able to reference them from context in which they are private, like any other method. Consequently you won't be able to pass private slots address to connect.

If you declare signal as private you are saying that only this class can manage it but function member pointers do not have access restrictions:

class A{
    private:
    void e(){

    }
    public:
    auto getPointer(){
        return &A::e;   
    }
};

int main()
{
    A a;
    auto P=a.getPointer();
    (a.*P)();
}

Other than that, what other answers mention is valid too:
- you still can connect private signals and slots from outside with tricks
- signals and slots are empty macros and do not break language standard