Qt-interest Archive, April 2007
SIGNAL emitted but SLOT never called
Message 1 in thread
Hi list,
in the following snippet the SIGNAL is definitely emitted (added a cout
in the SIGNAL in the moc file), but the corresponding SLOT is never
called even though both classes have Q_OBJECT included and inherit from
QObject or a QWidget. Maybe i am missing a very important point, but
since last evening i haven't been able to find the mistake.
TexiProject *tp = _store->getCurrentProject();
connect(tp, SIGNAL(bibtexItemAddedToProject(TexiProjectBibtexItem *)),
_ptw, SLOT(addBibtexItem(TexiProjectBibtexItem *)));
connect(tp, SIGNAL(bibtexItemAddedToProject(TexiProjectBibtexItem *)),
_proc, SLOT(addBibtexItem(TexiProjectBibtexItem *)));
The objects _ptw and _proc both have a SLOT with the same name which
does something different though.
I appreciate any help/advice/hint...
Christian Rengstl M.A.
Klinik und Poliklinik fÃr Innere Medizin II
Kardiologie - Forschung
UniversitÃtsklinikum Regensburg
B3 1.388
Franz-Josef-Strauss-Allee 11
93053 Regensburg
Tel.: +49-941-944-7230
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Message 2 in thread
Hi Christian,
connect fails when you use custom datatypes in your signals/slots unless
you declare your own datatypes with Q_DECLARE_METATYPE.
Regards,
Thomas
Christian Rengstl schrieb:
> Hi list,
>
> in the following snippet the SIGNAL is definitely emitted (added a cout
> in the SIGNAL in the moc file), but the corresponding SLOT is never
> called even though both classes have Q_OBJECT included and inherit from
> QObject or a QWidget. Maybe i am missing a very important point, but
> since last evening i haven't been able to find the mistake.
>
> TexiProject *tp = _store->getCurrentProject();
> connect(tp, SIGNAL(bibtexItemAddedToProject(TexiProjectBibtexItem *)),
> _ptw, SLOT(addBibtexItem(TexiProjectBibtexItem *)));
> connect(tp, SIGNAL(bibtexItemAddedToProject(TexiProjectBibtexItem *)),
> _proc, SLOT(addBibtexItem(TexiProjectBibtexItem *)));
>
> The objects _ptw and _proc both have a SLOT with the same name which
> does something different though.
>
> I appreciate any help/advice/hint...
>
>
> Christian Rengstl M.A.
> Klinik und Poliklinik fÃr Innere Medizin II
> Kardiologie - Forschung
> UniversitÃtsklinikum Regensburg
> B3 1.388
> Franz-Josef-Strauss-Allee 11
> 93053 Regensburg
> Tel.: +49-941-944-7230
>
> --
> To unsubscribe - send a mail to qt-interest-request@xxxxxxxxxxxxx with "unsubscribe" in the subject or the body.
> List archive and information: http://lists.trolltech.com/qt-interest/
>
>
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[ signature omitted ]
Message 3 in thread
On 12.04.07 12:41:36, Thomas Dähling wrote:
> connect fails when you use custom datatypes in your signals/slots unless you
> declare your own datatypes with Q_DECLARE_METATYPE.
Thats wrong.
> Christian Rengstl schrieb:
> >Hi list,
> >in the following snippet the SIGNAL is definitely emitted (added a cout
> >in the SIGNAL in the moc file), but the corresponding SLOT is never
> >called even though both classes have Q_OBJECT included and inherit from
> >QObject or a QWidget. Maybe i am missing a very important point, but
> >since last evening i haven't been able to find the mistake.
> >TexiProject *tp = _store->getCurrentProject();
> >connect(tp, SIGNAL(bibtexItemAddedToProject(TexiProjectBibtexItem *)),
> > _ptw, SLOT(addBibtexItem(TexiProjectBibtexItem *)));
> >connect(tp, SIGNAL(bibtexItemAddedToProject(TexiProjectBibtexItem *)),
> > _proc, SLOT(addBibtexItem(TexiProjectBibtexItem *)));
> >The objects _ptw and _proc both have a SLOT with the same name which
> >does something different though.
Do you get any error messages while running your program? Can you post a
minimal compilable example that reproduces the problem?
Andreas
--
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Message 4 in thread
Christian Rengstl schrieb:
> Hi list,
> ...
> TexiProject *tp = _store->getCurrentProject();
> connect(tp, SIGNAL(bibtexItemAddedToProject(TexiProjectBibtexItem *)),
> _ptw, SLOT(addBibtexItem(TexiProjectBibtexItem *)));
> connect(tp, SIGNAL(bibtexItemAddedToProject(TexiProjectBibtexItem *)),
> _proc, SLOT(addBibtexItem(TexiProjectBibtexItem *)));
The above looks syntactically correct to me, so here are the Usual Suspects:
- Watch on the console for suspicious "No such signal/slot" Qt messages
- Make sure the path of execution actually hits your "connect"
statements above, /before/ you expect your slot being called; which
seems vey logic, off course, but depending on your context you
might have a "frenchConnection()" (which connects all signals/slots
of a given class) method and you forgot to call it from within the
d'tor, for example
- Make sure the moc_files are updated when changing the corresponding
*.h files. When in doubt do a "make distclean" and/or remove
all moc_* files manually, then recompile from scratch
- Even though you did not get it wrong above, but the following cannot
be stressed enough (and it's a typical copy/paste-mistake not only
done by beginners):
DON'T write any argument names in the connect statement!
// WRONG
connect(tp, SIGNAL(bibtexItemAddedToProject(Item *item)),
_proc, SLOT(addBibtexItem(Item *item)));
Hope that gives you some leads.
Cheers, Oliver
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Message 5 in thread
Till Oliver Knoll schrieb:
> ...
> of a given class) method and you forgot to call it from within the
> d'tor, for example
^^^^^
c'tor, off course ;)
(Am I the only person who reads his posts /after/ he has sent them?)
;)
Cheers, Oliver
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Message 6 in thread
I think I may have a similar problem. Like you I had two classes that had identically named slots, so something like:
classA::mySlot();
classB::mySlot();
Then in my code I had:
classA* A;
classB* B;
connect(someButton, SIGNAL(clicked()), A, SLOT(mySlot()));
connect(someButton, SIGNAL(clicked()), B, SLOT(mySlot()));
So the idea was that when "someButton" was clicked, slots in both A and B would get called. However when I ran it, classA::mySlot() would get called TWICE and classB::mySlot() would never get called. I changed the names of the functions to:
classA::mySlotA();
classB::mySlotB();
And changed my connect statements to match the new functions names and the problem went away. I never filed a bug on this because at the time I was on a deadline, but as soon as I read your question I remembered it. Maybe I'll try to see if I can come up with a minimum compilable example...
So in your case are either slot (the one in _ptw and the one in _proc) getting called? Is it getting called twice?
Sean
-----Original Message-----
From: Christian Rengstl [mailto:Christian.Rengstl@xxxxxxxxxxxxxxxxxxxxxxxx]
Sent: Thursday, April 12, 2007 6:36 AM
To: qt-interest@xxxxxxxxxxxxx
Subject: SIGNAL emitted but SLOT never called
Hi list,
in the following snippet the SIGNAL is definitely emitted (added a cout in the SIGNAL in the moc file), but the corresponding SLOT is never called even though both classes have Q_OBJECT included and inherit from QObject or a QWidget. Maybe i am missing a very important point, but since last evening i haven't been able to find the mistake.
TexiProject *tp = _store->getCurrentProject(); connect(tp, SIGNAL(bibtexItemAddedToProject(TexiProjectBibtexItem *)),
_ptw, SLOT(addBibtexItem(TexiProjectBibtexItem *))); connect(tp, SIGNAL(bibtexItemAddedToProject(TexiProjectBibtexItem *)),
_proc, SLOT(addBibtexItem(TexiProjectBibtexItem *)));
The objects _ptw and _proc both have a SLOT with the same name which does something different though.
I appreciate any help/advice/hint...
Christian Rengstl M.A.
Klinik und Poliklinik für Innere Medizin II Kardiologie - Forschung Universitätsklinikum Regensburg
B3 1.388
Franz-Josef-Strauss-Allee 11
93053 Regensburg
Tel.: +49-941-944-7230
--
[ signature omitted ]
