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<p class="MsoNormal"><span style="color:#1F497D">Hi Mathias,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Yeah, this is what I knew in theory. Unfortunately this is not the case.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">You can try in python console. <o:p>
</o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Make sure you have a layer with some features.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Define function executeAfterSelection where you do some dummy printing.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Call three times layer.selectionChanged.connect(executeAfterSelection).<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Then try to select features in the layer.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">You will see the function executeAfterSelection is execute three times after each selection.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">I have done an workaround by introducing a flag variable which tells me if the myLayer.selectionChanged.connect(executeAfterSelection) statement was already called.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Thanks,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Marian<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span lang="EN-US" style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext;mso-fareast-language:EN-CA">From:</span></b><span lang="EN-US" style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext;mso-fareast-language:EN-CA">
Qgis-user [mailto:qgis-user-bounces@lists.osgeo.org] <b>On Behalf Of </b>Matthias Kuhn<br>
<b>Sent:</b> October-03-17 3:13 AM<br>
<b>To:</b> qgis-user@lists.osgeo.org<br>
<b>Subject:</b> Re: [Qgis-user] Check if a selectionChanged signal is connected to any slot?<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p>Hi Marian,<o:p></o:p></p>
<p>Just tell Qt that it shouldn't create the connection more than once using Qt::UniqueConnection.<o:p></o:p></p>
<p>Cheers<o:p></o:p></p>
<p>Matthias<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On 10/2/17 5:30 PM, Tudorache, Marian wrote:<o:p></o:p></p>
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<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">Hi everyone,<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">I have connected the signal selectionChanged so some code, which is executed after features are selected.<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">myLayer.selectionChanged.connect(self.executeAfterSelection)<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">Then I have a method self. executeAfterSelection(self, featuresIds)<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">The SIGNAl/SLOT tandem works but now I realized every time when I call
<b>myLayer.selectionChanged.connect(self.executeAfterSelection)</b> 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.<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">How can I check if the SIGNAL selectionChanged is connected to the slot executeAfterSelection before I run myLayer.selectionChanged.connect(self.executeAfterSelection)?<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">I tried this:<o:p></o:p></p>
<p class="MsoNormal">receiversCount = QtCore.QObject.receivers(QtCore.SIGNAL(“selectionChanged()”)<o:p></o:p></p>
<p class="MsoNormal">receiversCount = QtCore.QObject.receivers(QtCore.SIGNAL(“selectionChanged”)<o:p></o:p></p>
<p class="MsoNormal">receiversCount = QtCore.QObject.receivers(QtCore.SIGNAL(“myLayer.selectionChanged()”)<o:p></o:p></p>
<p class="MsoNormal">receiversCount = QtCore.QObject.receivers(QtCore.SIGNAL(“myLayer.selectionChanged”)<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">Every time I get this error:<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">QObject.receivers(SIGNAL()): first argument of unbound method must have type ‘QObject’).<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">Thanks,<o:p></o:p></p>
<p class="MsoNormal">Marian<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Times New Roman","serif";mso-fareast-language:EN-CA"><o:p> </o:p></span></p>
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