为什么不会用Q_OBJECT宏编译（链接）到位？ [英] Why won't this compile (link) with the Q_OBJECT macro in place?

问题描述

我使用PyQt制作了一个项目的原型，并使它在那里工作，现在我试图将其转换为C ++，并有一些问题。

I made a prototype of a project with PyQt and made it work there, now I'm trying to convert it to C++ and am having some problems.

我不把Q_OBJECT宏，它编译和工作，但如果我注释掉，我得到以下错误：

If I don't put the Q_OBJECT macro in, it compiles and works, but if I comment it out, I get the following errors:

Undefined symbols:
  "vtable for MapView", referenced from:
      MapView::~MapView()in mapview.o
      MapView::~MapView()in mapview.o
      MapView::MapView(QObject*)in mapview.o
      MapView::MapView()in mapview.o
  "MapView::staticMetaObject", referenced from:
      MapView::MapView(QObject*)in mapview.o
      MapView::MapView()in mapview.o

这是标题：

#ifndef MAPVIEW_H
#define MAPVIEW_H

#include <QtGui>
#include <QObject>

class MapView : public QGraphicsScene
{
    //Q_OBJECT

public:
    MapView();
    explicit MapView(QObject *parent = 0);
    QGraphicsPixmapItem *mappixmap;
    ~MapView();

private:
    bool dragging;
    float offsetX, offsetY, downoffsetX, downoffsetY;

protected:
    void mousePressEvent(QGraphicsSceneMouseEvent *event);
    void mouseMoveEvent(QGraphicsSceneMouseEvent *event);
    void mouseReleaseEvent(QGraphicsSceneMouseEvent *event);

};

#endif // MAPVIEW_H

我只是在这里省略Q_OBJECT宏？

Secondary question is will Bad Things happen if I just omit the Q_OBJECT macro here?

是的，我知道这是愚蠢的调用QGraphicsScene一个视图。

And yes, I'm aware of that it's stupid to call a QGraphicsScene a "view".

推荐答案

这种错误通常发生在你添加 Q_OBJECT 宏并忘记重新运行 moc 。如果使用 qmake ，只需在添加宏后运行 make qmake 。

This kind of errors usually happen when you add the Q_OBJECT macro and forget to rerun moc. If you use qmake, just run make qmake after you added the macro.

对于你的第二个问题：在没有 Q_OBJECT 宏的情况下，你将不能使用信号/槽（以及其他）。有关此问题的详情，请参见文档。

As for your second question: you won't be able to use signals/slots (among other things) without the Q_OBJECT macro. See the docs for more information about this.

这篇关于为什么不会用Q_OBJECT宏编译（链接）到位？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！