[Qt-interest] Optionally deriving from QWidget

[Tony Rietwyk]

Hi David, 

 

You always need at least QObject and the Q_OBJECT macro to do signal/slots,
so the non-gui class needs those.  

 

In my case, I have separate projects - one for the gui, and one for console,
each with different flags, and each outputting intermediate files to
different folders.  (Otherwise you need to rebuild a single project whenever
you change the compiler flag).  

 

Hope that helps, 

 

Tony.

 

 

 

From: qt-interest-bounces+tony.rietwyk=rightsoft.com.au at qt.nokia.com
[mailto:qt-interest-bounces+tony.rietwyk=rightsoft.com.au at qt.nokia.com] On
Behalf Of David Doria
Sent: Friday, 16 September 2011 7:32 AM
To: qt-interest at qt.nokia.com
Subject: [Qt-interest] Optionally deriving from QWidget

 

I have a class that emits Qt signals. I want to use this class in two ways:

 

1) Interactive - I want to use this class as part of a Qt GUI application
that can handle the signals.

2) Non-interactive - I want to use this class in a command line application
that does not know about Qt.

 

I tried defining a compiler flag INTERACTIVE and then doing something like
this:

 

#ifndef FORM_H

#define FORM_H

 

#if defined(INTERACTIVE)

#warning "Using interactive!"

#include <QWidget>

class Form : public QWidget

#else

#warning "Not using interactive!"

class Form

#endif

{

  #if defined(INTERACTIVE)

    Q_OBJECT

  

public:

    

  

  public slots:

    

  #endif

};

 

#endif

 

but even when the flag is defined, I get some vtable errors.

 

CMakeFiles/interactive.dir/interactive.cpp.o: In function `Form':

/media/portable/Examples/c++/src/QT/OptionalQt/form.h:14: undefined
reference to `vtable for Form'

/media/portable/Examples/c++/src/QT/OptionalQt/form.h:14: undefined
reference to `vtable for Form'

CMakeFiles/interactive.dir/interactive.cpp.o: In function `~Form':

/media/portable/Examples/c++/src/QT/OptionalQt/form.h:14: undefined
reference to `vtable for Form'

/media/portable/Examples/c++/src/QT/OptionalQt/form.h:14: undefined
reference to `vtable for Form'

 

Is this the right way to go about this? Can anyone explain where I went
wrong?

 

Thanks,

David

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.qt-project.org/pipermail/qt-interest-old/attachments/20110916/ffe12770/attachment.html