c – QObject继承Ambiguous Base

发布时间：2020-12-16 10:30:16 所属栏目：百科来源：网络整理

导读：我有一个简单的类,当我的程序获得并失去焦点时停止并启动一个计时器,但是它给出了错误,即QObject是每个信号槽连接上的MyApp的模糊基础. 这是相关代码： class MyApp : public QApplication,public QObject{ Q_OBJECT ...} 这是我的(凌乱)Main.cpp： #include

我有一个简单的类,当我的程序获得并失去焦点时停止并启动一个计时器,但是它给出了错误,即QObject是每个信号槽连接上的MyApp的模糊基础.
这是相关代码：

class MyApp : public QApplication,public QObject
{
    Q_OBJECT
    ...
}

这是我的(凌乱)Main.cpp：

#include <QtGui/QApplication>
    #include "qmlapplicationviewer.h"
    #include <QObject>
    #include <QGraphicsObject>
    #include <QTimer>
    #include <QVariant>
    #include "timecontrol.h"
    #include "scorecontrol.h"
    #include "Retry.h"
    #include <QEvent>
    #include "myapp.h"

    int main(int argc,char *argv[])
    {
        MyApp app(argc,argv);

        QmlApplicationViewer viewer;
        viewer.setOrientation(QmlApplicationViewer::ScreenOrientationLockLandscape);
        viewer.setMainQmlFile(QLatin1String("qml/Raker/main.qml"));
        viewer.showExpanded();

        QObject *rootObject = viewer.rootObject();

        QTimer *timmer = new QTimer;
        timmer->setInterval(1000);

        TimeControl *timcon = new TimeControl;

        scorecontrol *scorer = new scorecontrol;

        Retry *probeer = new Retry;

        QObject::connect(timmer,SIGNAL(timeout()),timcon,SLOT(updateTime()));
        QObject::connect(timcon,SIGNAL(setTime(QVariant)),rootObject,SLOT(setTime(QVariant)));
        QObject::connect(rootObject,SIGNAL(blockClicked(int,int)),scorer,SLOT(checkRight(int,int)));
        QObject::connect(scorer,SIGNAL(setScore(QVariant)),SLOT(setScore(QVariant)));
        QObject::connect(scorer,SIGNAL(setState(QVariant)),SLOT(setState(QVariant)));

        QObject::connect(rootObject,SIGNAL(start()),probeer,SLOT(Reetry()));
        QObject::connect(probeer,timmer,SLOT(start()));
        QObject::connect(probeer,SIGNAL(stop()),SLOT(stop()));
        QObject::connect(probeer,SIGNAL(start(int)),SLOT(randomNum(int)));
        QObject::connect(probeer,SIGNAL(sReset()),SLOT(reset()));
        QObject::connect(probeer,SIGNAL(tReset()),SLOT(reset()));
        QObject::connect(timcon,SIGNAL(timeOut()),SLOT(reset()));

        QObject::connect(timcon,SLOT(setState(QVariant)));
        QObject::connect(timcon,SIGNAL(changeFinal()),SLOT(changeFinal()));
        QObject::connect(scorer,SIGNAL(setFinal(QVariant)),SLOT(setFinal(QVariant)));

        QObject::connect(&app,SIGNAL(focusL()),SLOT(focusL()));
        QObject::connect(&app,SIGNAL(focusG()),SLOT(focusG()));

        return app.exec();
    }

MyApp.cpp中：

#include "myapp.h"
    #include <QDebug>
    #include <QObject>

    MyApp::MyApp(int argc,char **argv): QApplication(argc,argv)
    {
        installEventFilter(this);
    }

    bool MyApp::eventFilter(QObject *object,QEvent *event)
    {
        if (event->type() == QEvent::ApplicationDeactivate)
        {
            qDebug() << "Focus lost";
            focusL();
        }
        if (event->type() == QEvent::ApplicationActivate)
        {
            qDebug() << "Focus gained";
            focusG();
        }

        return false;
    }

解决方法

在您当前的示例中,您已经创建了一个拆分继承方案,其中您的对象最终得到了QObject的双实例… QApplication有一个基本QObject,而实际的MyApp类有另一个.这会产生歧义,因为访问继承的QObject方法或数据成员将无法准确知道要访问哪个继承的基础对象.

现在,您的继承图如下所示(请注意MyApp对象继承的两个QObject实例)：

| QObject |         | QObject |
                        /
                 | QApplication |
                      /
                     /
         |    MyApp    |

您应该保持继承图是线性的,而不是使用拆分继承方案,这意味着拥有一个只包含一个基类实例的派生类.所以你想要这样的东西：

QObject
       |
       |
  QApplication
       |
       |
     MyApp

（编辑：李大同）

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