Re: [Traverso-devel] Linker error (vtable) when adding a new command class

[Remon Sijrier]

Hi Peter,

If there is the macro Q_OBJECT in the header file you created, you'll have to 
add the source file also to the moc_sources in the CMakeList.txt file.

That should fix it, if not, please let me know.


Regards,

Remon

> Hello!
>
> I am still trying to add a new command "SheetPartSelection" to Traverso.
> Unfortunately I'm getting linker errors.
>
> * I created a new class SheetPartSelection which inherits from Command. Two
> new files,
>
> > src/commands/SheetPartSelection.h
> > src/commands/SheetPartSelection.cpp.
>
> * I created an entry for SheetPartSelection.cpp in
> src/commands/CMakeLists.txt (added manually)
>
> > SET(TRAVERSO_COMMANDS_SOURCES
> > [...]
> > SheetPartSelection.cpp
> > )
>
> * In SheetPartSelection.h I override all virtual methods mentioned in
> Command.h
>
> >         SheetPartSelection              (SheetView* sv);
> >         ~SheetPartSelection             ();
> >
> >         int     begin_hold              ();
> >         int     finish_hold             ();
> >         int     prepare_actions         ();
> >         int     do_action               ();
> >         int     undo_action             ();
> >         int     jog                     ();
> >         void    cancel_action           ();
> >         void    set_cursor_shape        (int useX, int useY);
> >         void    set_collected_number    (const QString& collected);
>
> * In SheetPartSelection.cpp I implement all methods mentioned in
> SheetPartSelection.h
>
> This all compiles fine, but when it comes to linking, I get this vtable 
error:
> > /home/peter/Documents/programming/traverso/0.42.0/dev/02_cvs/traverso_0.4
> >2.0-003/lib/libtraversocommands.a(SheetPartSelection.o): In function
> > `SheetPartSelection::~SheetPartSelection()':
> > SheetPartSelection.cpp:(.text+0x1d1): undefined reference to `vtable for
> > SheetPartSelection'
> > /home/peter/Documents/programming/traverso/0.42.0/dev/02_cvs/traverso_0.4
> >2.0-003/lib/libtraversocommands.a(SheetPartSelection.o): In function
> > `SheetPartSelection::~SheetPartSelection()':
> > SheetPartSelection.cpp:(.text+0x261): undefined reference to `vtable for
> > SheetPartSelection'
> > /home/peter/Documents/programming/traverso/0.42.0/dev/02_cvs/traverso_0.4
> >2.0-003/lib/libtraversocommands.a(SheetPartSelection.o): In function
> > `SheetPartSelection::~SheetPartSelection()':
> > SheetPartSelection.cpp:(.text+0x2e1): undefined reference to `vtable for
> > SheetPartSelection' make[2]: Leaving directory
> > `/home/peter/Documents/programming/traverso/0.42.0/dev/02_cvs/traverso_0.
> >42.0-003' make[1]: Leaving directory
> > `/home/peter/Documents/programming/traverso/0.42.0/dev/02_cvs/traverso_0.
> >42.0-003'
> > /home/peter/Documents/programming/traverso/0.42.0/dev/02_cvs/traverso_0.4
> >2.0-003/lib/libtraversocommands.a(SheetPartSelection.o): In function
> > `SheetPartSelection::SheetPartSelection(SheetView*)':
> > SheetPartSelection.cpp:(.text+0x39e): undefined reference to `vtable for
> > SheetPartSelection'
> > /home/peter/Documents/programming/traverso/0.42.0/dev/02_cvs/traverso_0.4
> >2.0-003/lib/libtraversocommands.a(SheetPartSelection.o): In function
> > `SheetPartSelection::SheetPartSelection(SheetView*)':
> > SheetPartSelection.cpp:(.text+0x47e): undefined reference to `vtable for
> > SheetPartSelection' collect2: ld returned 1 exit status
> > make[2]: *** [bin/traverso] Error 1
> > make[1]: *** [buildfiles/CMakeFiles/traverso.dir/all] Error 2
> > make: *** [all] Error 2
> > *** Exited with status: 2 ***
>
> According to some literature on the internet this error is given if there
> are non-pure virtual methods declared but not implemented [1]. However, as
> far as I can see I did implement every virtual method in
> SheetPartSelection.cpp.
>
> * What have I overlooked?
> * Is there a simpler way of adding new files to the project without having
> to hand edit the CMakeLists.txt file?
>
> Thank you very much for your consideration!
>
> P
>
>
>
>
>
>
>
>
> --------
>
> Some specifics of my machine:
> I am using KDevelop 3.5.1 on KDE 3.5.9.
>
> > address@hidden:~$ gcc --version
> > gcc (GCC) 4.2.3 (Ubuntu 4.2.3-2ubuntu7)
> >
> > address@hidden:~$ cat /etc/issue
> > Ubuntu 8.04.1 \n \l
> >
> > address@hidden:~$ uname -a
> > Linux localhost 2.6.24-19-generic #1 SMP Fri Jul 11 21:01:46 UTC 2008
> > x86_64 GNU/Linux
>
> --------
>
> src/commands/SheetPartSelection.h
>
> > //
> > // C++ Interface: SheetSelection
> > //
> > // Description:
> > //
> > //
> > // Author: Peter Hoppe <>, (C) 2008
> > //
> > // Copyright: See COPYING file that comes with this distribution
> > //
> > //
> > #ifndef SHEETPARTSELECTION_H
> > #define SHEETPARTSELECTION_H
> >
> > #include "Command.h"
> >
> > class SheetView;
> > class QPoint;
> >
> > /**
> >  * A command which creates a selection area over part of a sheet. All
> > audio clip parts within that area will * be split off and mixed down to a
> > new clip. That clip can then be inserted somewhere else. *
> >  * @author Peter Hoppe
> >  */
> > class SheetPartSelection : public Command
> > {
> >     Q_OBJECT
> >     Q_CLASSINFO("select", tr("Select"));
> >
> >     public:
> >         SheetPartSelection              (SheetView* sv);
> >         ~SheetPartSelection             ();
> >
> >         int     begin_hold              ();
> >         int     finish_hold             ();
> >         int     prepare_actions         ();
> >         int     do_action               ();
> >         int     undo_action             ();
> >         int     jog                     ();
> >         void    cancel_action           ();
> >         void    set_cursor_shape        (int useX, int useY);
> >         void    set_collected_number    (const QString& collected);
> >
> >     private:
> >         SheetView*      m_sv;
> > };
> >
> > #endif
>
> src/commands/SheetPartSelection.cpp
>
> > //
> > // C++ Implementation: SheetSelection
> > //
> > // Description:
> > //
> > //
> > // Author: Peter Hoppe <address@hidden>, (C) 2008
> > //
> > // Copyright: See COPYING file that comes with this distribution
> > //
> > //
> > #include "SheetPartSelection.h"
> >
> > #include "SheetView.h"
> > #include "Sheet.h"
> > #include "ClipsViewPort.h"
> > #include "ContextPointer.h"
> > #include <QPoint>
> >
> > // Always put me below _all_ includes, this is needed
> > // in case we run with memory leak detection enabled!
> > #include "Debugger.h"
> >
> > SheetPartSelection::SheetPartSelection (SheetView* sv)
> >
> >  : Command ("Select")
> >
> > {
> >     PENTERCONS;
> >     m_sv = sv;
> > }
> >
> >
> > SheetPartSelection::~SheetPartSelection()
> > {
> >     PENTERDES;
> > }
> >
> >
> > int SheetPartSelection::begin_hold()
> > {
> >     PENTER;
> >     return 0;
> > }
> >
> > int SheetPartSelection::finish_hold()
> > {
> >     PENTER;
> >     return 0;
> > }
> >
> > int SheetPartSelection::prepare_actions()
> > {
> >     PENTER;
> >     return 0;
> > }
> >
> > int SheetPartSelection::do_action()
> > {
> >     PENTER;
> >     return 0;
> > }
> >
> > int SheetPartSelection::undo_action()
> > {
> >     PENTER;
> >     return 0;
> > }
> >
> > int SheetPartSelection::jog()
> > {
> >     PENTER;
> >     return 0;
> > }
> >
> > void SheetPartSelection::cancel_action()
> > {
> >     PENTER;
> > }
> >
> > void SheetPartSelection::set_cursor_shape (int useX, int useY)
> > {
> >     PENTER;
> > }
> >
> > void set_collected_number (const QString& collected)
> > {
> >     PENTER;
> > }
>
> --------
> [1] http://gcc.gnu.org/faq.html#vtables
>    
> http://www.storkyak.com/2006/07/gnu-c-undefined-reference-to-vtable.html