[Qgis-user] Check if a selectionChanged signal is connected to any slot?

[Matthias Kuhn]

Hi Marian,

Just tell Qt that it shouldn't create the connection more than once
using Qt::UniqueConnection.

Cheers

Matthias


On 10/2/17 5:30 PM, Tudorache, Marian wrote:
>
>  
>
> Hi everyone,
>
>  
>
> I have connected the signal selectionChanged so some code, which is
> executed after features are selected.
>
>  
>
> myLayer.selectionChanged.connect(self.executeAfterSelection)
>
>  
>
> Then I have a method self. executeAfterSelection(self, featuresIds)
>
>  
>
> The SIGNAl/SLOT tandem works but now I realized every time when I call
> *myLayer.selectionChanged.connect(self.executeAfterSelection)*  It
> does not overwrite my previous call. It creates a second signa/slot
> tandem. During running the method  executeAfterSelection is excuted
> twice, three times etc.
>
>  
>
> How can I check if the SIGNAL selectionChanged is connected to the
> slot executeAfterSelection before I run
> myLayer.selectionChanged.connect(self.executeAfterSelection)?
>
>  
>
> I tried this:
>
> receiversCount =
> QtCore.QObject.receivers(QtCore.SIGNAL(“selectionChanged()”)
>
> receiversCount =
> QtCore.QObject.receivers(QtCore.SIGNAL(“selectionChanged”)
>
> receiversCount =
> QtCore.QObject.receivers(QtCore.SIGNAL(“myLayer.selectionChanged()”)
>
> receiversCount =
> QtCore.QObject.receivers(QtCore.SIGNAL(“myLayer.selectionChanged”)
>
>  
>
> Every time I get this error:
>
>  
>
> QObject.receivers(SIGNAL()): first argument of unbound method must
> have type ‘QObject’).
>
>  
>
>  
>
> Thanks,
>
> Marian
>
>  
>
>  
>
>  
>
>
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