[PySide] signal connection only works with lambda

[Cristián Maureira-Fredes]

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
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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
--