从QMainWindow和Ui_MainWindow继承一个主窗口类。

I am learning Qt, Qt 5. When I start Qt Creator and create a project with ALL the default settings, I get these 2 files generated, (I am excluding main.cpp and the .pro file)

我正在学习Qt, Qt 5。当我启动Qt创建者并创建一个包含所有默认设置的项目时，我将生成这两个文件(我不包括main)。cpp和。pro文件

mainwindow.h

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();

private:
    Ui::MainWindow *ui;
};

#endif // MAINWINDOW_H

---

mainwindow.cpp

mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
}

MainWindow::~MainWindow()
{
    delete ui;
}

---

Now, I prefer to do it this way,

现在，我更喜欢这样做，

my_mainwindow.h

my_mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include "ui_mainwindow.h"


class MainWindow : public QMainWindow, private Ui_MainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
};

#endif // MAINWINDOW_H

---

my_mainwindow.cpp

my_mainwindow.cpp

#include "my_mainwindow.h"
#include <QMessageBox>

MainWindow::MainWindow(QWidget *parent) :   QMainWindow(parent)
{
    setupUi(this);
}

MainWindow::~MainWindow()
{

}

---

Here are the main differences between my code and Qt Creator's code:

以下是我的代码和Qt创建者的代码之间的主要区别:

1. No namespace Ui in my code. (Could anyone explain me the use of this namespace here ?)
2. 我的代码中没有名称空间Ui。(有人能解释一下这个名称空间的用法吗?)
3. I inherit the MainWindow class from both QMainWindow and Ui_MainWindow whereas the Qt Creator's code inherits it only from the QMainWindow class.
4. 我从QMainWindow和Ui_MainWindow继承了MainWindow类，而Qt创建者的代码仅从QMainWindow类继承它。

My question is, is there ANY disadvantage of using my approach or is there any advantage of using the Qt Creator's approach ? Please give a detailed answer.

我的问题是，使用我的方法有什么缺点吗?或者使用Qt创建者的方法有什么好处?请给出详细的答案。

1 个解决方案

#1

1. An advantage of the namespace is that it prevents naming *es. All the automatically generated names from QtDesigner stay in their own namespace.
2. 命名空间的优点是它可以防止命名冲突。所有来自QtDesigner的自动生成的名称都保留在它们自己的名称空间中。
3. An advantage of making the Ui class a member, instead of using multiple inheritance, is that the Ui class only needs to be forward-declarded in the header. In your code, you have a #include "ui_mainwindow.h", and that in turn drags in a lot of includes from QtWidgets like <QLabel>, <QPushButton> etc. This decreases compilation speed significantly, as everyone who includes mainwindow.h now also includes those QtWidgets includes. When using the Ui class as a member and forward-declaring it, all these includes only need to be compiled when compiling mainwindow.cpp, but not when including mainwindow.h from somewhere else.
4. 使Ui类成为成员而不是使用多重继承的优点是，Ui类只需要在头中声明。在您的代码中，有一个#include“ui_mainwindow”。h“，而这又会使很多包括qtwidget(比如 )、 等等)的内容减少，这大大降低了编译速度，因为每个人都包括mainwindow。h现在还包含了那些QtWidgets。当使用Ui类作为成员并向前声明时，所有这些都只需要在编译主窗口时编译。cpp，但不包括主窗口。从别的地方h。