Signals from inherited widgets

[pippo42]

Hello,

I have created a class that inherits from QTableView and given it a signal. When I try to connect to it, I have an error message, at run time, that says that QTableView has no such signal but the object I am using is an instance of the class I have inherited from QTableView.

What I am doing wrong?

Here a sample of code that will make things clearer.

class MyTableView : public QTableView{
   ...
signals:
   void mySignal(int);
};

class MyTableView : public QTableView{
   ...
signals:
   void mySignal(int);
};

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MyTableView *myTableView=new MyTableView();
connect(myTableView, SIGNAL(mySignal(int)), ...

MyTableView *myTableView=new MyTableView();
connect(myTableView, SIGNAL(mySignal(int)), ...

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At run time, I have the error message:

Object::connect: No such signal QTableView::mySignal(int)

Object::connect: No such signal QTableView::mySignal(int)

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Thank you!

[mrvk]

Did you use the macro Q_OBJECT in the class declaration ?

class MyTableView : public QTableView{
Q_OBJECT
   ...
signals:
   void mySignal(int);
};

class MyTableView : public QTableView{
Q_OBJECT
   ...
signals:
   void mySignal(int);
};

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[pippo42]

Thank you for your reply.

I have tried with and without the Q_OBJECT macro.

When I include Q_OBJECT in the class declaration, I have error messages saying "undefined reference to vtable for MyTableView". But all the functions are defined. It happens also if I define the signal (but I am not supposed to do this?).

[mrvk]

If you need to use signals and slots, then you need to use the macro, Q_OBJECT.

Regarding your error, just take a look at this thread. Hope it helps.

http://www.qtcentre.org/threads/2840...ghlight=vtable

[BalaQT]

u need to include Q_OBJECT macro

as mrvk mentioned
http://www.qtcentre.org/threads/2840...ghlight=vtable
this thread holds the following ans

Re: Qt Undefined Reference to vtable

Typically, if you get "Undefined Reference to vtable" whilst building a project you need to ensure MOC is being run. The easiest way to ensure this is to simply run qmake from the QtCreator menu bar and then rebuild the project. Q_OBJECT is only required if your class needs signals or slots - these are then read by MOC and parsed into another file that it creates and automatically adds to your project. Without this file, you get the vtable error.

Bala

[pippo42]

Thank you very much to all of you!

Problem solved!