Re: [PyQt] why do closeEvent and destroyed slot not get called on accepting PyQt4 QDialog?
fantastic!, that was exactly the penny drop I was missing! Lessons learned: 1. Don't hook handler for destroyed signal onto the object being destroyed. (seems obvious in retrospect) 2. QDialog.accept() does not fire closeEvent, even though it does get destroyed - bug or documentation is misleading IMHO 3. The different syntax for hooking up to the signal - much simpler and more pythonic Now I can get rid of the sip.isdeleted(obj) workaround in my actual code, yech! Many thanks! -- View this message in context: http://old.nabble.com/why-do-closeEvent-and-destroyed-slot-not-get-called-on-accepting-PyQt4-QDialog--tp31336229p31349767.html Sent from the PyQt mailing list archive at Nabble.com. ___ PyQt mailing listPyQt@riverbankcomputing.com http://www.riverbankcomputing.com/mailman/listinfo/pyqt
Re: [PyQt] why do closeEvent and destroyed slot not get called on accepting PyQt4 QDialog?
On Thursday 07 April 2011, 17:27:15 Rui DaCosta wrote:
> Firstly thanks again for your reply,
>
> In the original code, from where this simplification is based, I have
> cleanup code on both closeEvent and destroyed, but...
>
> that's just the problem, the closeEvent isn't getting fired (unless I
> manually call close) - except when the window is closed from the
> close box.
>
> I was expecting that from the docs for done(), I would not have to on
> done(), ie. is this a bug? or are the docs incorrect?
>
> And separately, destroyed is a signal according to the docs
> http://www.riverbankcomputing.co.uk/static/Docs/PyQt4/html/qobject.ht
>ml#destroyed
>
>
> but I cannot get it to fire for QDialog, no matter what I do,
> including manually calling destroy().
>
> The object appears deleted when inspected with sip.isdeleted, even
> before the destroy() - so if that is the case, why does it not raise
> a destroyed signal?
Well, looks like this is an issue in Heisenbergs uncertainty principle
domain ;-)
It's simply the GC, that's in the way. If you anchor the connect
somewhere else, the destroyed signal "gets though". If your real dialog
has a parent, you might get away with anchoring the connect there.
import sys
from PyQt4.QtGui import *
from PyQt4.QtCore import *
def pr(arg):
sys.stdout.write(arg + "\n")
sys.stdout.flush()
class Dialog(QDialog):
def __init__(self):
QDialog.__init__(self, None, Qt.WindowFlags(Qt.WA_DeleteOnClose))
self.button_box = QDialogButtonBox(self)
self.button_box.addButton(self.button_box.Ok)
self.button_box.accepted.connect(self.on_accept)
layout = QVBoxLayout()
layout.addWidget(self.button_box)
#self.setAttribute(Qt.WA_DeleteOnClose)
self.setLayout(layout)
self.destroyed.connect(self.on_destroyed)
def on_destroyed(self, *args):
pr("destroying dialog")
def on_accept(self):
pr("accepting")
self.done(42)
def closeEvent(self, event):
pr("close")
return QDialog.closeEvent(self, event)
app = QApplication([])
widget = Dialog()
widget.destroyed.connect(lambda: pr("destroyed"))
result = widget.exec_()
del widget
#my_widget.destroy()
print("result: %s" % result)
>
>
>
>
>
> ____________
> From: Demetrius Cassidy
> To: Rui DaCosta
> Cc: pyqt@riverbankcomputing.com
> Sent: Thu, 7 April, 2011 17:02:04
> Subject: Re: [PyQt] why do closeEvent and destroyed slot not get
> called on accepting PyQt4 QDialog?
>
>
> I truly believe you are approaching this from the wrong angle. If you
> need to know when your QDialog is going away, you override closeEvent
> and do your cleanup from there.
>
> However, looking through the docs, it does not appear that destroy is
> actually a signal. It's called from the QWidget dtor, so it makes
> sense that if you call destroy(), you get the runtime error because
> you are deleting the C++ object before the Python object. Do not call
> destroy yourself - call self.close and override closeEvent. From
> there you can accept or reject closing the dialog, and do any cleanup
> prior to your dialog being destroyed.
>
> From the Qt Docs:
>
> void QWidget::destroy ( bool destroyWindow = true, bool
> destroySubWindows = true ) [protected]
>
> Frees up window system resources. Destroys the widget window if
> destroyWindow is true.
>
> destroy() calls itself recursively for all the child widgets, passing
> destroySubWindows for the destroyWindow parameter. To have more
> control over destruction of subwidgets, destroy subwidgets
> selectively first.
>
> This function is usually called from the QWidget destructor.
>
>
> On Thu, Apr 7, 2011 at 3:04 AM, Rui DaCosta wrote:
>
> I know it can close it manually, the problem is that this is a
> simplification of a problem I had, in which we were expecting the
> QDialog to close as per the docs, but it did not.
>
> >The *real* problem we are facing, is a bit further down the line,
> > where we are getting the "RuntimeError: underlying C/C++ object has
> > been deleted" but we never receive a destroyed signal.
> >The only reason I need this signal or event is to do some teardown
> > code for some callbacks to avoid getting this c++ error elsewhere.
>
>
> From: Demetrius Cassidy
>
> >To: RuiDC
> >Sent: Thu, 7 April, 2011 0:39:33
> >Subject: Re: [PyQt] why do closeEvent and destroyed slot not get
> > called on accepting PyQt4 QDialog?
> >
> >
> >If you want to close, just call self.close. It's a slot, so you can
> > map it to any
Re: [PyQt] why do closeEvent and destroyed slot not get called on accepting PyQt4 QDialog?
just to be clear, I wasn't trying to use destroy(), I was merely using it to demonstrate that even if I did, neither the closeEvent nor the destroyed signal were working. From: Demetrius Cassidy To: Rui DaCosta Cc: pyqt@riverbankcomputing.com Sent: Thu, 7 April, 2011 17:18:29 Subject: Re: [PyQt] why do closeEvent and destroyed slot not get called on accepting PyQt4 QDialog? Sorry found destroyed() - that's what happens when you reply to emails before you have morning coffee. Anyway I'm not sure why destroyed() is never fired. I tried your code and even modified it a bit to use the new style slots and signals but it's not being fired. Either way, I think the other points I raised in my last email are still valid. IMHO using destroyed() in python is the wrong approach. On Thu, Apr 7, 2011 at 11:02 AM, Demetrius Cassidy wrote: I truly believe you are approaching this from the wrong angle. If you need to know when your QDialog is going away, you override closeEvent and do your cleanup from there. > > >However, looking through the docs, it does not appear that destroy is actually >a >signal. It's called from the QWidget dtor, so it makes sense that if you call >destroy(), you get the runtime error because you are deleting the C++ object >before the Python object. Do not call destroy yourself - call self.close and >override closeEvent. From there you can accept or reject closing the dialog, >and >do any cleanup prior to your dialog being destroyed. > > >From the Qt Docs: > > >void QWidget::destroy ( bool destroyWindow = true, bool destroySubWindows = >true >) [protected] > >Frees up window system resources. Destroys the widget window if destroyWindow >is >true. > >destroy() calls itself recursively for all the child widgets, passing >destroySubWindows for the destroyWindow parameter. To have more control over >destruction of subwidgets, destroy subwidgets selectively first. > >This function is usually called from the QWidget destructor. > > > >On Thu, Apr 7, 2011 at 3:04 AM, Rui DaCosta wrote: > >I know it can close it manually, the problem is that this is a simplification >of >a problem I had, in which we were expecting the QDialog to close as per the >docs, but it did not. >>The *real* problem we are facing, is a bit further down the line, where we >>are >>getting the "RuntimeError: underlying C/C++ object has been deleted" but we >>never receive a destroyed signal. >>The only reason I need this signal or event is to do some teardown code for >>some >>callbacks to avoid getting this c++ error elsewhere. >> >> >> >> From: Demetrius Cassidy >>To: RuiDC >>Sent: Thu, 7 April, 2011 0:39:33 >>Subject: Re: [PyQt] why do closeEvent and destroyed slot not get called on >>accepting PyQt4 QDialog? >> >> >>If you want to close, just call self.close. It's a slot, so you can map it to >>any signal. Also not sure why you want to know when your widget is destroyed? >>Let Python take care of it, you should not need to call sip.delete yourself. >>closeEvent is there if you need to know _when_ your app was requested to >>close. >>If you want to allow or reject closing the app, you need to use the QEvent >>object which gets passed to that function. >> >> >>On Wed, Apr 6, 2011 at 5:27 PM, RuiDC wrote: >> >> >>>The question & code are here: >>>http://stackoverflow.com/questions/5570402/why-do-closeevent-and-destroyed-slot-not-get-called-on-accepting-pyqt4-qdialog >>> >>> >>>but hopefully someone here can give me an answer on: >>>1. how to get the closeEvent to fire from accepting (or do I have to do a >>>self.close()?) >>>2. how to get the destroyed message to print (or do I have to go through >>>sip.delete(my_widget)?) >>>3. why, if I comment out the del my_widget, and uncomment the >>>my_widget.destroy() I get a: >>>RuntimeError: underlying C/C++ object has been deleted >>>on the destroy() without the print! i.e. how is it that it can be destroyed >>>but not raise the signal? >>> >>>Thanks in advance, >>>R >>>-- >>>View this message in context: >>>http://old.nabble.com/why-do-closeEvent-and-destroyed-slot-not-get-called-on-accepting-PyQt4-QDialog--tp31336229p31336229.html >>> >>>Sent from the PyQt mailing list archive at Nabble.com. >>> >>>___ >>>PyQt mailing listPyQt@riverbankcomputing.com >>>http://www.riverbankcomputing.com/mailman/listinfo/pyqt >>> >> > ___ PyQt mailing listPyQt@riverbankcomputing.com http://www.riverbankcomputing.com/mailman/listinfo/pyqt
Re: [PyQt] why do closeEvent and destroyed slot not get called on accepting PyQt4 QDialog?
Firstly thanks again for your reply, In the original code, from where this simplification is based, I have cleanup code on both closeEvent and destroyed, but... that's just the problem, the closeEvent isn't getting fired (unless I manually call close) - except when the window is closed from the close box. I was expecting that from the docs for done(), I would not have to on done(), ie. is this a bug? or are the docs incorrect? And separately, destroyed is a signal according to the docs http://www.riverbankcomputing.co.uk/static/Docs/PyQt4/html/qobject.html#destroyed but I cannot get it to fire for QDialog, no matter what I do, including manually calling destroy(). The object appears deleted when inspected with sip.isdeleted, even before the destroy() - so if that is the case, why does it not raise a destroyed signal? From: Demetrius Cassidy To: Rui DaCosta Cc: pyqt@riverbankcomputing.com Sent: Thu, 7 April, 2011 17:02:04 Subject: Re: [PyQt] why do closeEvent and destroyed slot not get called on accepting PyQt4 QDialog? I truly believe you are approaching this from the wrong angle. If you need to know when your QDialog is going away, you override closeEvent and do your cleanup from there. However, looking through the docs, it does not appear that destroy is actually a signal. It's called from the QWidget dtor, so it makes sense that if you call destroy(), you get the runtime error because you are deleting the C++ object before the Python object. Do not call destroy yourself - call self.close and override closeEvent. From there you can accept or reject closing the dialog, and do any cleanup prior to your dialog being destroyed. From the Qt Docs: void QWidget::destroy ( bool destroyWindow = true, bool destroySubWindows = true ) [protected] Frees up window system resources. Destroys the widget window if destroyWindow is true. destroy() calls itself recursively for all the child widgets, passing destroySubWindows for the destroyWindow parameter. To have more control over destruction of subwidgets, destroy subwidgets selectively first. This function is usually called from the QWidget destructor. On Thu, Apr 7, 2011 at 3:04 AM, Rui DaCosta wrote: I know it can close it manually, the problem is that this is a simplification of a problem I had, in which we were expecting the QDialog to close as per the docs, but it did not. >The *real* problem we are facing, is a bit further down the line, where we are >getting the "RuntimeError: underlying C/C++ object has been deleted" but we >never receive a destroyed signal. >The only reason I need this signal or event is to do some teardown code for >some >callbacks to avoid getting this c++ error elsewhere. > > > > From: Demetrius Cassidy >To: RuiDC >Sent: Thu, 7 April, 2011 0:39:33 >Subject: Re: [PyQt] why do closeEvent and destroyed slot not get called on >accepting PyQt4 QDialog? > > >If you want to close, just call self.close. It's a slot, so you can map it to >any signal. Also not sure why you want to know when your widget is destroyed? >Let Python take care of it, you should not need to call sip.delete yourself. >closeEvent is there if you need to know _when_ your app was requested to >close. >If you want to allow or reject closing the app, you need to use the QEvent >object which gets passed to that function. > > >On Wed, Apr 6, 2011 at 5:27 PM, RuiDC wrote: > > >>The question & code are here: >>http://stackoverflow.com/questions/5570402/why-do-closeevent-and-destroyed-slot-not-get-called-on-accepting-pyqt4-qdialog >> >> >>but hopefully someone here can give me an answer on: >>1. how to get the closeEvent to fire from accepting (or do I have to do a >>self.close()?) >>2. how to get the destroyed message to print (or do I have to go through >>sip.delete(my_widget)?) >>3. why, if I comment out the del my_widget, and uncomment the >>my_widget.destroy() I get a: >>RuntimeError: underlying C/C++ object has been deleted >>on the destroy() without the print! i.e. how is it that it can be destroyed >>but not raise the signal? >> >>Thanks in advance, >>R >>-- >>View this message in context: >>http://old.nabble.com/why-do-closeEvent-and-destroyed-slot-not-get-called-on-accepting-PyQt4-QDialog--tp31336229p31336229.html >> >>Sent from the PyQt mailing list archive at Nabble.com. >> >>___ >>PyQt mailing listPyQt@riverbankcomputing.com >>http://www.riverbankcomputing.com/mailman/listinfo/pyqt >> > ___ PyQt mailing listPyQt@riverbankcomputing.com http://www.riverbankcomputing.com/mailman/listinfo/pyqt
Re: [PyQt] why do closeEvent and destroyed slot not get called on accepting PyQt4 QDialog?
Sorry found destroyed() - that's what happens when you reply to emails before you have morning coffee. Anyway I'm not sure why destroyed() is never fired. I tried your code and even modified it a bit to use the new style slots and signals but it's not being fired. Either way, I think the other points I raised in my last email are still valid. IMHO using destroyed() in python is the wrong approach. On Thu, Apr 7, 2011 at 11:02 AM, Demetrius Cassidy wrote: > I truly believe you are approaching this from the wrong angle. If you need > to know when your QDialog is going away, you override closeEvent and do your > cleanup from there. > > However, looking through the docs, it does not appear that destroy is > actually a signal. It's called from the QWidget dtor, so it makes sense that > if you call destroy(), you get the runtime error because you are deleting > the C++ object before the Python object. Do not call destroy yourself - call > self.close and override closeEvent. From there you can accept or reject > closing the dialog, and do any cleanup prior to your dialog being destroyed. > > From the Qt Docs: > > void QWidget::destroy ( bool destroyWindow = true, bool destroySubWindows = > true ) [protected] > > Frees up window system resources. Destroys the widget window if > destroyWindow is true. > > destroy() calls itself recursively for all the child widgets, passing > destroySubWindows for the destroyWindow parameter. To have more control over > destruction of subwidgets, destroy subwidgets selectively first. > > This function is usually called from the QWidget destructor. > > On Thu, Apr 7, 2011 at 3:04 AM, Rui DaCosta wrote: > >> I know it can close it manually, the problem is that this is a >> simplification of a problem I had, in which we were expecting the QDialog to >> close as per the docs, but it did not. >> The *real* problem we are facing, is a bit further down the line, where we >> are getting the "RuntimeError: underlying C/C++ object has been deleted" >> but we never receive a destroyed signal. >> The only reason I need this signal or event is to do some teardown code >> for some callbacks to avoid getting this c++ error elsewhere. >> >> ------------------ >> *From:* Demetrius Cassidy >> *To:* RuiDC >> *Sent:* Thu, 7 April, 2011 0:39:33 >> *Subject:* Re: [PyQt] why do closeEvent and destroyed slot not get called >> on accepting PyQt4 QDialog? >> >> If you want to close, just call self.close. It's a slot, so you can map it >> to any signal. Also not sure why you want to know when your widget is >> destroyed? Let Python take care of it, you should not need to call >> sip.delete yourself. closeEvent is there if you need to know _when_ your app >> was requested to close. If you want to allow or reject closing the app, you >> need to use the QEvent object which gets passed to that function. >> >> On Wed, Apr 6, 2011 at 5:27 PM, RuiDC wrote: >> >>> >>> The question & code are here: >>> >>> http://stackoverflow.com/questions/5570402/why-do-closeevent-and-destroyed-slot-not-get-called-on-accepting-pyqt4-qdialog >>> >>> but hopefully someone here can give me an answer on: >>> 1. how to get the closeEvent to fire from accepting (or do I have to do a >>> self.close()?) >>> 2. how to get the destroyed message to print (or do I have to go through >>> sip.delete(my_widget)?) >>> 3. why, if I comment out the del my_widget, and uncomment the >>> my_widget.destroy() I get a: >>> RuntimeError: underlying C/C++ object has been deleted >>> on the destroy() without the print! i.e. how is it that it can be >>> destroyed >>> but not raise the signal? >>> >>> Thanks in advance, >>> R >>> -- >>> View this message in context: >>> http://old.nabble.com/why-do-closeEvent-and-destroyed-slot-not-get-called-on-accepting-PyQt4-QDialog--tp31336229p31336229.html >>> Sent from the PyQt mailing list archive at Nabble.com. >>> >>> ___ >>> PyQt mailing listPyQt@riverbankcomputing.com >>> http://www.riverbankcomputing.com/mailman/listinfo/pyqt >>> >> >> > ___ PyQt mailing listPyQt@riverbankcomputing.com http://www.riverbankcomputing.com/mailman/listinfo/pyqt
Re: [PyQt] why do closeEvent and destroyed slot not get called on accepting PyQt4 QDialog?
I truly believe you are approaching this from the wrong angle. If you need to know when your QDialog is going away, you override closeEvent and do your cleanup from there. However, looking through the docs, it does not appear that destroy is actually a signal. It's called from the QWidget dtor, so it makes sense that if you call destroy(), you get the runtime error because you are deleting the C++ object before the Python object. Do not call destroy yourself - call self.close and override closeEvent. From there you can accept or reject closing the dialog, and do any cleanup prior to your dialog being destroyed. >From the Qt Docs: void QWidget::destroy ( bool destroyWindow = true, bool destroySubWindows = true ) [protected] Frees up window system resources. Destroys the widget window if destroyWindow is true. destroy() calls itself recursively for all the child widgets, passing destroySubWindows for the destroyWindow parameter. To have more control over destruction of subwidgets, destroy subwidgets selectively first. This function is usually called from the QWidget destructor. On Thu, Apr 7, 2011 at 3:04 AM, Rui DaCosta wrote: > I know it can close it manually, the problem is that this is a > simplification of a problem I had, in which we were expecting the QDialog to > close as per the docs, but it did not. > The *real* problem we are facing, is a bit further down the line, where we > are getting the "RuntimeError: underlying C/C++ object has been deleted" > but we never receive a destroyed signal. > The only reason I need this signal or event is to do some teardown code for > some callbacks to avoid getting this c++ error elsewhere. > > -- > *From:* Demetrius Cassidy > *To:* RuiDC > *Sent:* Thu, 7 April, 2011 0:39:33 > *Subject:* Re: [PyQt] why do closeEvent and destroyed slot not get called > on accepting PyQt4 QDialog? > > If you want to close, just call self.close. It's a slot, so you can map it > to any signal. Also not sure why you want to know when your widget is > destroyed? Let Python take care of it, you should not need to call > sip.delete yourself. closeEvent is there if you need to know _when_ your app > was requested to close. If you want to allow or reject closing the app, you > need to use the QEvent object which gets passed to that function. > > On Wed, Apr 6, 2011 at 5:27 PM, RuiDC wrote: > >> >> The question & code are here: >> >> http://stackoverflow.com/questions/5570402/why-do-closeevent-and-destroyed-slot-not-get-called-on-accepting-pyqt4-qdialog >> >> but hopefully someone here can give me an answer on: >> 1. how to get the closeEvent to fire from accepting (or do I have to do a >> self.close()?) >> 2. how to get the destroyed message to print (or do I have to go through >> sip.delete(my_widget)?) >> 3. why, if I comment out the del my_widget, and uncomment the >> my_widget.destroy() I get a: >> RuntimeError: underlying C/C++ object has been deleted >> on the destroy() without the print! i.e. how is it that it can be >> destroyed >> but not raise the signal? >> >> Thanks in advance, >> R >> -- >> View this message in context: >> http://old.nabble.com/why-do-closeEvent-and-destroyed-slot-not-get-called-on-accepting-PyQt4-QDialog--tp31336229p31336229.html >> Sent from the PyQt mailing list archive at Nabble.com. >> >> ___ >> PyQt mailing listPyQt@riverbankcomputing.com >> http://www.riverbankcomputing.com/mailman/listinfo/pyqt >> > > ___ PyQt mailing listPyQt@riverbankcomputing.com http://www.riverbankcomputing.com/mailman/listinfo/pyqt
[PyQt] why do closeEvent and destroyed slot not get called on accepting PyQt4 QDialog?
The question & code are here: http://stackoverflow.com/questions/5570402/why-do-closeevent-and-destroyed-slot-not-get-called-on-accepting-pyqt4-qdialog but hopefully someone here can give me an answer on: 1. how to get the closeEvent to fire from accepting (or do I have to do a self.close()?) 2. how to get the destroyed message to print (or do I have to go through sip.delete(my_widget)?) 3. why, if I comment out the del my_widget, and uncomment the my_widget.destroy() I get a: RuntimeError: underlying C/C++ object has been deleted on the destroy() without the print! i.e. how is it that it can be destroyed but not raise the signal? Thanks in advance, R -- View this message in context: http://old.nabble.com/why-do-closeEvent-and-destroyed-slot-not-get-called-on-accepting-PyQt4-QDialog--tp31336229p31336229.html Sent from the PyQt mailing list archive at Nabble.com. ___ PyQt mailing listPyQt@riverbankcomputing.com http://www.riverbankcomputing.com/mailman/listinfo/pyqt
