Re: [PyQt] Strange behavior with new-style signals and slots
Message: 1 Date: Sun, 01 Apr 2012 13:04:30 +0200 From: Detlev Offenbach det...@die-offenbachs.de To: pyqt@riverbankcomputing.com Subject: [PyQt] Strange behavior with new-style signals and slots Message-ID: 1362374.ZZnnlU3EYs@jupiter Content-Type: text/plain; charset=us-ascii Hallo, I am observing a strange behavior related to new-style signal and slots. Here is the situation. My program calls this line twice in a class (via different code paths). self.project.projectPropertiesChanged.connect(self.__projectPropertiesChanged) The disconnect is only issued once when the class (the editor) is closed. self.project.projectPropertiesChanged.disconnect(self.__projectPropertiesChanged) If the signal is emitted thereafter, I get a RuntimeError saying, that the underlying C/C++ object has been destroyed. I suspect, that the Python wrapper for the Qt object (here it is a QScintilla object) is still kept alive by some reference counter (possibly caused by the double connection). Is this a bug in PyQt/sip or do I have to avoid such a situation? If the later is the case, is it possible to check, if a signal is already connected, e.g. something like self.project.projectPropertiesChanged.is_connected(self.__projectPropertiesChanged) Another consequence of the double connection is, that the slot is called twice when the signal is emitted. Regards, Detlev -- Detlev Offenbach det...@die-offenbachs.de Detlev, Perhaps you want to make use of Qt::UniqueConnection as the connection type. Note that I believe this will only work correctly on a slot decorated with pyqtSlot (or that was previously the case anyhow) - MH ___ PyQt mailing listPyQt@riverbankcomputing.com http://www.riverbankcomputing.com/mailman/listinfo/pyqt
[PyQt] Strange behavior with new-style signals and slots
Hallo, I am observing a strange behavior related to new-style signal and slots. Here is the situation. My program calls this line twice in a class (via different code paths). self.project.projectPropertiesChanged.connect(self.__projectPropertiesChanged) The disconnect is only issued once when the class (the editor) is closed. self.project.projectPropertiesChanged.disconnect(self.__projectPropertiesChanged) If the signal is emitted thereafter, I get a RuntimeError saying, that the underlying C/C++ object has been destroyed. I suspect, that the Python wrapper for the Qt object (here it is a QScintilla object) is still kept alive by some reference counter (possibly caused by the double connection). Is this a bug in PyQt/sip or do I have to avoid such a situation? If the later is the case, is it possible to check, if a signal is already connected, e.g. something like self.project.projectPropertiesChanged.is_connected(self.__projectPropertiesChanged) Another consequence of the double connection is, that the slot is called twice when the signal is emitted. Regards, Detlev -- Detlev Offenbach det...@die-offenbachs.de ___ PyQt mailing listPyQt@riverbankcomputing.com http://www.riverbankcomputing.com/mailman/listinfo/pyqt
Re: [PyQt] Strange behavior with new-style signals and slots
On Sun, 01 Apr 2012 13:04:30 +0200, Detlev Offenbach det...@die-offenbachs.de wrote: Hallo, I am observing a strange behavior related to new-style signal and slots. Here is the situation. My program calls this line twice in a class (via different code paths). self.project.projectPropertiesChanged.connect(self.__projectPropertiesChanged) The disconnect is only issued once when the class (the editor) is closed. self.project.projectPropertiesChanged.disconnect(self.__projectPropertiesChanged) If the signal is emitted thereafter, I get a RuntimeError saying, that the underlying C/C++ object has been destroyed. I suspect, that the Python wrapper for the Qt object (here it is a QScintilla object) is still kept alive by some reference counter (possibly caused by the double connection). Is this a bug in PyQt/sip or do I have to avoid such a situation? I can't tell from your description - you need to provide a test case. Making the same connection twice is technically possible, but sounds like an application bug to me. If the later is the case, is it possible to check, if a signal is already connected, e.g. something like self.project.projectPropertiesChanged.is_connected(self.__projectPropertiesChanged) Another consequence of the double connection is, that the slot is called twice when the signal is emitted. ...which is what you would expect. Phil ___ PyQt mailing listPyQt@riverbankcomputing.com http://www.riverbankcomputing.com/mailman/listinfo/pyqt
