error when adding signal slot to a QGLWidget based class

[john_god]

I have a QGLWidget based class that worked fine untill I add a signal slot
connection, so I can use a context menu, like the menu example in Qt assitant (only I'm
using it in a QGLWidget instead of the main window).
My class:

#include <QGLWidget>
#include <QMenu>
#include <QObject>
 
class GLGraph : public QGLWidget
{
   // Q_OBJECT // this line causes the error
 
public:
    GLGraph();
    ~GLGraph();
.....
protected:
    virtual void contextMenuEvent(QContextMenuEvent *event);
 
...
private:
.....
    void createActions();
    QAction *newInterpolAct;
....
private slots:
    void newInterpol();

#include <QGLWidget>
#include <QMenu>
#include <QObject>

class GLGraph : public QGLWidget
{
   // Q_OBJECT // this line causes the error

public:
    GLGraph();
    ~GLGraph();
.....
protected:
    virtual void contextMenuEvent(QContextMenuEvent *event);

...
private:
.....
    void createActions();
    QAction *newInterpolAct;
....
private slots:
    void newInterpol();

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void GLGraph::contextMenuEvent(QContextMenuEvent *event)
{
    if (!flag_Interpolation)
        return;
 
    QMenu menu(this);
    menu.addAction(newInterpolAct);
    menu.exec(event->globalPos());
}
 
void GLGraph::createActions()
 {
     newInterpolAct = new QAction(tr("&New"), this);
     newInterpolAct->setShortcuts(QKeySequence::New);
    // newInterpolAct->setStatusTip(tr("Create a new Interpolation"));
     connect(newInterpolAct, SIGNAL(triggered()), this, SLOT(newInterpolAct()));
}
 
void GLGraph::newInterpol()
{
    QMessageBox::about(this,"","nova interpol");
 
}

void GLGraph::contextMenuEvent(QContextMenuEvent *event)
{
    if (!flag_Interpolation)
        return;

    QMenu menu(this);
    menu.addAction(newInterpolAct);
    menu.exec(event->globalPos());
}

void GLGraph::createActions()
 {
     newInterpolAct = new QAction(tr("&New"), this);
     newInterpolAct->setShortcuts(QKeySequence::New);
    // newInterpolAct->setStatusTip(tr("Create a new Interpolation"));
     connect(newInterpolAct, SIGNAL(triggered()), this, SLOT(newInterpolAct()));
}

void GLGraph::newInterpol()
{
    QMessageBox::about(this,"","nova interpol");

}

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My errors:

D:/qt4examples/Matematica/glgraph.cpp:9: undefined reference to `vtable for GLGraph'
D:/qt4examples/Matematica/glgraph.cpp:9: undefined reference to `vtable for GLGraph'
D:/qt4examples/Matematica/glgraph.cpp:9: undefined reference to `vtable for GLGraph'
D:/qt4examples/Matematica/glgraph.cpp:9: undefined reference to `vtable for GLGraph'
D:/qt4examples/Matematica/glgraph.cpp:41: undefined reference to `vtable for GLGraph'
D:/qt4examples/Matematica/glgraph.cpp:41: undefined reference to `vtable for GLGraph'
:-1: error: collect2: ld returned 1 exit status

D:/qt4examples/Matematica/glgraph.cpp:9: undefined reference to `vtable for GLGraph'
D:/qt4examples/Matematica/glgraph.cpp:9: undefined reference to `vtable for GLGraph'
D:/qt4examples/Matematica/glgraph.cpp:9: undefined reference to `vtable for GLGraph'
D:/qt4examples/Matematica/glgraph.cpp:9: undefined reference to `vtable for GLGraph'
D:/qt4examples/Matematica/glgraph.cpp:41: undefined reference to `vtable for GLGraph'
D:/qt4examples/Matematica/glgraph.cpp:41: undefined reference to `vtable for GLGraph'
:-1: error: collect2: ld returned 1 exit status

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The error occurs when I use Q_OBJECT in the class declaration. The lines 9 and 41 are
the first bracket lines of the construtor and destructor. If I remove the Q_OBJECT the
program works, the context menus apears but doesnt connect and I get a message in the
Qtcreator compile output window:

Object::connect: No such slot QGLWidget::newInterpolAct() in glgraph.cpp:439

Object::connect: No such slot QGLWidget::newInterpolAct() in glgraph.cpp:439

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this line is:

connect(newInterpolAct, SIGNAL(triggered()), this, SLOT(newInterpolAct()));

connect(newInterpolAct, SIGNAL(triggered()), this, SLOT(newInterpolAct()));

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Any ideas on this error ???????????

[wysota]

Always run qmake after adding the macro to an existing file.

[john_god]

THANK YOU very much

Also had other stupid mistake, I had:

connect(newInterpolAct, SIGNAL(triggered()), this, SLOT(newInterpolAct()));

connect(newInterpolAct, SIGNAL(triggered()), this, SLOT(newInterpolAct()));

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instead of:

connect(newInterpolAct, SIGNAL(triggered()), this, SLOT(newInterpol()));

connect(newInterpolAct, SIGNAL(triggered()), this, SLOT(newInterpol()));

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Works fine now !!!!!