如何在C ++中通过类结构共享代码？

Question

I am writing for the Qt framework and I want to create a QWidget. QWidget exposes some interfaces such as mousePressEvent and mouseReleaseEvent. I want to extend this class to allow mouseClickEvent and mouseDoubleClickEvent. Normally, you would think to extend QWidget and implement those functions. The problem is that there are other classes (QPushButton for example) provided as part of the library which extend QWidget. Therefore, how do I get that added functionality into those classes without having to extend each one and copy the code?

class ClickHandeler : public QWidget {
    virtual void mouseClickEvent();
    virtual void mouseDoubleClickEvent();

    int clickCount; //initialized to 0;

    void mouseReleaseEvent(QEvent *event){
        clickCount++;
        QTimer::singleShot(500, this, SLOT(checkClick()));
    }

    void checkClick(){
        if (clickCount == 2){
            this->mouseDoubleClickEvent();
            clickCount = clickCount-2;
        } else {
            this->mouseDoubleEvent()
            clickCount--;
        }
    }
}

// QPushButton inherits QWidget too! Yikes!
class MyPushButton : public QPushButton, public ClickHandeler {
    void mouseClickEvent(){
        alert("i have been clicked");
    }

    void mouseDoubleClickEvent(){
        alert("i have been double clicked");
    }
}

I want something like MyPushButton, but I am worried that the function overriding will not work as expected.

Im sorry if this question is obvious to people, but I do not know what the terminology is. I have googled interfaces for c++ and I get abstract interfaces (which doesnt properly solve this problem). If I'm just being stupid and need to know a better term for google, let me know in the comments and Ill remove the question.

Answer 1

I think you just need to extend the QWidget and call the QWidget same functions. For example:

class QWidget {
public:
    void mouseClickEvent();
};

class QPushButton {
public:
    void mouseClickEvent();
};

class MyWidget : public QWidget, public QPushButton {
public:
    void mouseClickEvent()
    {
        //base::mouseClickEvent();// ambiguous
        QWidget::mouseClickEvent();
        QPushButton::mouseClickEvent();
        /* Do your own code here */
    }
};