[Interest] Debugging not emitted signals

Nuno Santos nunosantos at imaginando.pt
Fri Jul 31 11:18:16 CEST 2015


I found the problem. I was being completely eluded. 

I was modifying an object that was not being displayed. Also, I was trying to debug objects that were never being modified to trigger the signals.

That’s why I couldn’t see the signals being emitted.

Conclusion: I need vacations!

Thanks for all your quick replies



> On 31 Jul 2015, at 09:58, André Somers <andre at familiesomers.nl> wrote:
> Op 31-7-2015 om 10:51 schreef Nuno Santos:
>> Hi,
>> I’m facing a weird issue. I have signal in a class that is not being emitted.
> How do you know this? My guess is: all you know is that your slots that 
> you think you connected to this signal are not getting called, but that 
> is not the same thing.
>> What can be causing this? How should I debug?
> Put a breakpoint at the emit line, and follow what happens from there.
>> I have tripple checked everything and can’t figure it out, why such a basic functionality is not working.
> You can be sure that the basic functionality _is_ working. In fact, it 
> is a safe assumption to make when you start debugging anything: the 
> error is in the code you wrote, and not in the libraries you are using. 
> Only occasionaly, you'll find that the bug actualy _is_ in the library, 
> but that will be the exception and not the rule, especially if it is 
> about basic, tried-and-tested functionality of that library like the 
> signal-slot system in Qt.
>> Can someone provide me some debugging tips for this case?
> Use the new style of connect (compile time checking) and again: use your 
> debugger.
> André
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