[PySide] signal connection only works with lambda

[Frank Rueter]

Hi Chritian,
sorry for the delay again. Yes, once I have a little bit more time I will
try and condense this into sharable code to report back with.

Cheers,
frank

On Thu, Sep 1, 2022 at 7:23 PM Cristián Maureira-Fredes <
Cristian.Maureira-Fredes at qt.io> wrote:

> Hey Frank,
>
> Could you maybe share more code using
> services like pastebin.com or any other?
>
> Images are a bit hard to understand, because
> often they lack of context.
>
> If you think you encounter a bug,
> maybe you can open a bug report,
> but for that, please share the code of a minimal reproducible
> example [1]
>
> Cheers
>
> [1] https://wiki.qt.io/Qt_for_Python/Reporting_Bugs
>
> On 9/1/22 06:00, Frank Rueter wrote:
> > Hi Christian,
> >
> > sorry for the delay.
> > Yes, the signal is declared in the class but not inside any function.
> > I had not used the @Slot decorator but tried it just now to no avail.
> > image.png
> > image.png
> > image.png
> >
> > On Tue, Aug 30, 2022 at 7:21 PM Cristián Maureira-Fredes
> > <Cristian.Maureira-Fredes at qt.io <mailto:Cristian.Maureira-Fredes at qt.io>>
>
> > wrote:
> >
> >
> >
> >     On 8/30/22 00:08, Frank Rueter wrote:
> >      > Hi all,
> >      >
> >
> >     Hey Frank,
> >
> >      > probably a pre-coffee hiccup:
> >      > I have this weird issue where my signal connection only works when
> >      > utilising lambda, even though the data type sent by the signal is
> >      > exactly what the receiving slot needs.
> >      > This is my code:
> >      >
> >      > In a worker class (QRunnable) I emit this signal
> >      > *    tasks_data_available = QtCore.Signal(list)
> >      > *
> >      >
> >
> >     Just a sanity check:
> >     That's declared inside a class, but not inside any method, right?
> >
> >      > In my main widget I connect it like this:
> >      > *
> worker.tasks_data_available.connect(self.__prep_task_data)
> >      > *
> >      > the slot looks like this:
> >      > *    def __prep_task_data(self, task_list):
> >      > *
> >      > *        print(task_list)*
> >
> >     Is this method decorated with a `@Slot(list)` ?
> >
> >     @Slot(list)
> >     def __prep_task_data(elf, task_list):
> >           ...
> >
> >      > I have done this countless times, but for some reason in this
> >     case the
> >      > code never calls the slot when the QRunnable emits task_list.
> >      >
> >      > When I do this it works though:
> >      > *        worker.tasks_data_available.connect(lambda t:
> >      > self.__prep_task_data(t))
> >      > *
> >
> >     This might be due to the lazy registration of the lambda as a Slot,
> >     without properly going through the Slot-registration process.
> >
> >      > What am I missing? I should not have to use lambda in this case.
> >
> >     It might be the missing @Slot,
> >     but let me know if that's not the case.
> >
> >      > Cheers,
> >      > frank
> >
> >
> >     Cheers
> >
> >     --
> >     Dr. Cristián Maureira-Fredes
> >     Senior R&D Manager
> >
> >     The Qt Company GmbH
> >     Erich-Thilo-Str. 10
> >     D-12489 Berlin
> >
> >     Geschäftsführer: Mika Pälsi,
> >     Juha Varelius, Jouni Lintunen
> >     Sitz der Gesellschaft: Berlin,
> >     Registergericht: Amtsgericht
> >     Charlottenburg, HRB 144331 B
> >     _______________________________________________
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> >
>
> --
> Dr. Cristian Maureira-Fredes
> Senior R&D Manager
>
> The Qt Company GmbH
> Erich-Thilo-Str. 10
> D-12489 Berlin
>
> Geschäftsführer: Mika Pälsi,
> Juha Varelius, Mika Harjuaho
> Sitz der Gesellschaft: Berlin,
> Registergericht: Amtsgericht
> Charlottenburg, HRB 144331 B
> --
>
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