QT中添加Q_OBJECT出现的问题
2012-03-28 23:22
267 查看
Multiple Inheritance Requires QObject to Be First(多重继承QObject一定要放在前面)
我在用class My_Node : public QGraphicsItem,public QObject来生成自己的类时,想使用信号和槽机制,但这是dys_node.h中没有Q_OBJECT,不能使用信号槽。我将Q_OBJECT加上之后,出现几个不知道是什么的错误。然后我将工程目录下的Makefile删除,然后重新编译、链接文件,刚才的错误消失了,但出现如下三个错误:
error: 'staticMetaObject' is not a member of 'QGraphicsItem'
error: 'qt_metacast' is not a member of 'QGraphicsItem'
error: 'qt_metacall' is not a member of 'QGraphicsItem'
通过google,我发现这个错误是由于没有继承QObject类而引起的,但是我已经继承了QObject类了啊,到底是怎么回事呢?
最后终于在网上找到了答案,当多继承的时候,要将QObject放在前面,即将类的声明改为
class My_Node : public QObject,public QGraphicsItem
问题就解决了!!!
下面是我从网络上找到的说明原文:
Just got this error message while compiling a tiny class that derives from QTreeWidgetItem:
error C2039: 'staticMetaObject' : is not a member of 'QTreeWidgetItem'
What this is saying is that QTreeWidgetItem does not inherit from QObject, meaning that your own, singly-inherited class also does not inherit from QObject. Inheriting from QObject is one of the prerequisites
to using the Q_OBJECT macro, which, if you’re anything like me, you automatically insert into any Qt GUI related class.
If you’re not using any of the meta object stuff in your subclass, such as signals/slots or properties, just take out the Q_OBJECT macro. If you need to use signals and slots, you’ll need to make your
subclass multiply-inherit from QObject as well. If you take this route, remember that “Multiple Inheritance Requires QObject to Be First”, otherwise you’ll get either the same error as above, or something along the lines of “YourClass inherits from two QObject
subclasses” from the moc。
我在用class My_Node : public QGraphicsItem,public QObject来生成自己的类时,想使用信号和槽机制,但这是dys_node.h中没有Q_OBJECT,不能使用信号槽。我将Q_OBJECT加上之后,出现几个不知道是什么的错误。然后我将工程目录下的Makefile删除,然后重新编译、链接文件,刚才的错误消失了,但出现如下三个错误:
error: 'staticMetaObject' is not a member of 'QGraphicsItem'
error: 'qt_metacast' is not a member of 'QGraphicsItem'
error: 'qt_metacall' is not a member of 'QGraphicsItem'
通过google,我发现这个错误是由于没有继承QObject类而引起的,但是我已经继承了QObject类了啊,到底是怎么回事呢?
最后终于在网上找到了答案,当多继承的时候,要将QObject放在前面,即将类的声明改为
class My_Node : public QObject,public QGraphicsItem
问题就解决了!!!
下面是我从网络上找到的说明原文:
Just got this error message while compiling a tiny class that derives from QTreeWidgetItem:
error C2039: 'staticMetaObject' : is not a member of 'QTreeWidgetItem'
What this is saying is that QTreeWidgetItem does not inherit from QObject, meaning that your own, singly-inherited class also does not inherit from QObject. Inheriting from QObject is one of the prerequisites
to using the Q_OBJECT macro, which, if you’re anything like me, you automatically insert into any Qt GUI related class.
If you’re not using any of the meta object stuff in your subclass, such as signals/slots or properties, just take out the Q_OBJECT macro. If you need to use signals and slots, you’ll need to make your
subclass multiply-inherit from QObject as well. If you take this route, remember that “Multiple Inheritance Requires QObject to Be First”, otherwise you’ll get either the same error as above, or something along the lines of “YourClass inherits from two QObject
subclasses” from the moc。
相关文章推荐
- QT中添加Q_OBJECT出现的问题
- QT中添加Q_OBJECT出现的问题
- QT中添加Q_OBJECT出现的问题 & Qt moc: error C2039
- QT中添加Q_OBJECT出现的问题
- QT中添加Q_OBJECT出现的问题
- QT中添加Q_OBJECT和继承QObject出现的问题
- QT添加rtmp库的时候出现问题
- 在QT添加QWebView是出现的问题
- Qt中在QMAinWindow内添加layout出现问题
- Windows Server 2003 添加/删除Windows组件出现错误的问题
- Windows Server 2003 添加/删除Windows组件出现错误的问题
- 关于ubantu下QT安装及新建项目时出现的问题
- QT使用QTcpSocket和QTcpServer通信是出现乱码的问题
- VS2010配置Qt4.8.6出现的问题
- QT添加组件储存库问题
- 最近开发一个项目使用了Nhibernate出现了如下问题deleted object would be re-saved by cascade (remove deleted object from
- magento 第四章 出现 "Fatal error:Call to a member function load() on a non-object in \Abstract.php" 问题
- qt QAxObject word文档添加页码(页眉和页脚)
- Qt工程在Linux下编译时出现.ui文件编译不通过的问题
- Qt4.8.5 开发环境搭建没有生成makefile文件【编译出现的问题】