我的課沒有完美的容器

Question

我有一個容器有很多問題的類，這次如果我用非默認構造函數創建我的對象我無法控制容器中的對象（更改價值，可見...）;但如果我用默認的構造函數定義我的對象，我可以很容易地做到這一點。

Control.h

class Controls : public QObject 
{ 

private: 

    QHBoxLayout *Layout ; 
    string Controlname; 
    QLabel *Label ; 

    QSpinBox *Spin ; 


public: 
    QSlider *Slider ; 
    Controls(QLayout &Parent , string name , const int &Default_value); 
    Controls(const Controls &copy); 
    Controls(); 
    Controls(QLayout &Parent); 
    ~Controls(); 


    QLabel * Get_Label()const { return Label ; } 
    QSlider * Get_Slider()const { return Slider ; } 
    QSpinBox * Get_Spin()const { return Spin ; } 
    QHBoxLayout * Get_Layout() {return Layout;} 

    void SetValue(const int &newvalue); 

    Controls &operator= (const Controls &copy); 


}; 

controls.cpp

#include "Interface.h" 
Controls &Controls::operator= (const Controls &copy) 
{ 
    Slider->setValue(copy.Get_Slider()->value()); 
    Slider->setOrientation(Qt::Horizontal); 
    Label->setText(copy.Get_Label()->text()); 
    Spin->setValue(copy.Get_Spin()->value()); 

    Layout->addWidget(Label , 0 , 0); 
    Layout->addWidget(Slider , 0 , 0); 
    Layout->addWidget(Spin , 0 , 0); 

    QObject::connect(Slider , SIGNAL(valueChanged(int)) , 
        Spin , SLOT(setValue(int))); 
    QObject::connect(Spin , SIGNAL(valueChanged(int)) , 
        Slider , SLOT(setValue(int))); 

    return *this; 
} 

Controls::Controls(const Controls &copy) 
{ 
    Label = new QLabel() ; 
    Slider = new QSlider() ; 
    Spin = new QSpinBox() ; 
    Layout = new QHBoxLayout(); 

    Slider->setValue(copy.Get_Slider()->value()); 
    Slider->setOrientation(Qt::Horizontal); 
    Label->setText(copy.Get_Label()->text()); 
    Spin->setValue(copy.Get_Spin()->value()); 

    Layout->addWidget(Label , 0 , 0); 
    Layout->addWidget(Slider , 0 , 0); 
    Layout->addWidget(Spin , 0 , 0); 

    QObject::connect(Slider , SIGNAL(valueChanged(int)) , 
        Spin , SLOT(setValue(int))); 
    QObject::connect(Spin , SIGNAL(valueChanged(int)) , 
        Slider , SLOT(setValue(int))); 
} 

Controls::Controls() 
{ 
    Label = new QLabel() ; 
    Slider = new QSlider() ; 
    Spin = new QSpinBox() ; 
    Layout = new QHBoxLayout(); 

    Slider->setValue(0); 
    Slider->setOrientation(Qt::Horizontal); 
    Label->setText(QString ("unamed")); 
    Spin->setValue(0); 


    Layout->addWidget(Label , 0 , 0); 
    Layout->addWidget(Slider , 0 , 0); 
    Layout->addWidget(Spin , 0 , 0); 

    QObject::connect(Slider , SIGNAL(valueChanged(int)) , 
        Spin , SLOT(setValue(int))); 
    QObject::connect(Spin , SIGNAL(valueChanged(int)) , 
        Slider , SLOT(setValue(int))); 
} 


Controls::Controls(QLayout &Parent , string name , const int &Default_value) 
{ 
    Controlname = name ; 

    Label = new QLabel() ; 
    Slider = new QSlider() ; 
    Spin = new QSpinBox() ; 
    Layout = new QHBoxLayout(); 

    Slider->setValue(Default_value); 
    Slider->setOrientation(Qt::Horizontal); 
    Label->setText(QString (name.c_str())); 
    Spin->setValue(Default_value); 


    Layout->addWidget(Label , 0 , 0); 
    Layout->addWidget(Slider , 0 , 0); 
    Layout->addWidget(Spin , 0 , 0); 

    QObject::connect(Slider , SIGNAL(valueChanged(int)) , 
        Spin , SLOT(setValue(int))); 
    QObject::connect(Spin , SIGNAL(valueChanged(int)) , 
        Slider , SLOT(setValue(int))); 

    Parent.addItem(Layout); 
} 

void Controls::SetValue(const int &newvalue) 
{ 
    Slider->setValue(newvalue); 
} 

Controls::~Controls() 
{ 
} 

的main.cpp

int main() 
{ 
    QApplication app (argc , argv); 

    QVBoxLayout layout ; 
    QLabel Image ; 
    QWidget Panel ; 
    Camera Cm ; 


    vector <Controls> g ; 
    g.push_back(Controls(layout ,"c1" , 33)); 
    g.push_back(Controls(layout ,"c2" , 13)); 
    g.push_back(Controls(layout ,"c3" , 63)); 
    g.push_back(Controls(layout ,"c1" , 33)); 


    for (int x =0 ; x<g.size() ; x++) 
    { 
    g.at(x).SetValue(33); ////not work 

    } 

    vector <Controls> g2 ; 
    g2.push_back(Controls()); 
    g2.push_back(Controls()); 
    g2.push_back(Controls()); 
    g2.push_back(Controls()); 


    for (int x =0 ; x<g2.size() ; x++) 
    { 
    layout.addItem(g2.at(x).Get_Layout()); 
    g2.at(x).SetValue(33); ////this work 

    } 


    Panel.setLayout(&layout); 
    Panel. show(); 

    return app.exec(); 

    return 0; 
} 

Answer 1

你不應該有Controls拷貝構造函數或賦值操作符在所有，你應該將類型Controls*的值存儲在向量中而不是typ e Controls。

創建GUI對象的複製構造函數非常值得懷疑。有一個原因QLabel,QSlider,QSpinBox和QHBoxLayout本身沒有拷貝構造函數。它會導致代碼非常慢，並很快變得混亂。

總之，你應該幾乎從不擁有從QObject繼承的對象的複製構造函數。