QMetaObject::connectSlotsByName: No matching signal for

今天发现qt程序在运行时命令行窗口会弹出下面的警告：

QMetaObject::connectSlotsByName: No matching signal for ...

但实际功能并没有受影响。网上google了一圈，终于找到原因。

 

以下转自：http://www.qtforum.org/article/20685/connectslotsbyname.html

After a bit of sleuthing to find the source of all the Qt warnings, “QMetaObject::connectSlotsByName: Nomatching signal for…”, in our log window/file, here’s what I’ve found.

setupUi calls connectSlotsByName. connectSlotsByName parses the moc_ file in order to connect slots andsignals. The moc_ file contains a list of all the slots for the class. The parser iterates over the list of slot names looking for the following pattern: on_objectName_signal, where on_objectName_signal is the name of the slot, objectName is the object name and signal is the signal. For example, if you have a slot named, on_doneButton_clicked(), the parser looks for an object named doneButton, a signal named clicked and then connects the on_doneButton_clicked() slot to QButton’s signal clicked().

If you follow this naming convention, you do not need to call the connect() method, nor do you need to connect the signal via the Qt UI editor in VisualStudio. connectSlotsByName will automatically make the connection for you.

So, in order to get rid of the “No matching signal for…” warnings, we need to either follow this naming convention, or make sure none of our slot names begin with “on_”. If you have a slot, onDoneButton_clicked,for example, connectSlotsByName will no try to connect it with a signal, nor will emit an warning.

 

上面大概就是说：用VistalStudio里的QtEditer可以自动调用Qt中“connectSlotsByName”即“按空间名称关联槽”的方式进行关联，对应的函数必须写成“on_控件名_信号名”的格式；或者也可以通过connet函数人为显式地将信号和槽关联起来。但是，如果采用显式connect的方法的同时，又将槽函数的名字起成了“on_控件名_信号名”的格式，那么就会在运行时弹出“QMetaObject::connectSlotsByName: No matching signal for”的警告了！