I closed a dialog, but it seems to be still running
-
@jsulm said in I closed a dialog, but it seems to be still running:
@MasterBlade said in I closed a dialog, but it seems to be still running:
I used some global variables in that file
Why global variables?!
What file?Please show your code at least.
It's a large file so I'll make it short. Just some global integers like
int gid = 0;
This is at the top of the .cpp file, followed by regular class definition.A::A(QWidget* parent) : QDialog(parent), ui(new Ui::A){ gid = 5; }There are other functions that further increases gid. like ++gid; When I close that window while gid is 7 and reopen it, gid is still 7. It's neither 0 or 5.
Also I have a qtimer, it will do something when time expired.
connect(timer, &QTimer::timeout, this, &A::something);I set a breakpoint at 'something'. The program will still pause at 'something' even if I close the window as if it's still running.
I also set a breakpoint at the destructor of the window. But it never runs, even if I close the whole application.
@MasterBlade
It sounds like yourint gid;is what you say, a global variable, not a member of yourAclass. So it has nothing to do with your class instances, and so will retain its value.Closing/re-opening a
QWidgetis not the same thing asnew/delete-ing it, so it would not reset a member variable anyway. Unless you setQt::WA_DeleteOnClose.Don't know about your breakpoint on closing the application, don't know if you have passed the parameters to put this
Ainstance into the widget hierarchy so it gets closed. -
@MasterBlade
It sounds like yourint gid;is what you say, a global variable, not a member of yourAclass. So it has nothing to do with your class instances, and so will retain its value.Closing/re-opening a
QWidgetis not the same thing asnew/delete-ing it, so it would not reset a member variable anyway. Unless you setQt::WA_DeleteOnClose.Don't know about your breakpoint on closing the application, don't know if you have passed the parameters to put this
Ainstance into the widget hierarchy so it gets closed.@JonB said in I closed a dialog, but it seems to be still running:
@MasterBlade
It sounds like yourint gid;is what you say, a global variable, not a member of yourAclass. So it has nothing to do with your class instances, and so will retain its value.Closing/re-opening a
QWidgetis not the same thing asnew/delete-ing it, so it would not reset a member variable anyway. Unless you setQt::WA_DeleteOnClose.Don't know about your breakpoint on closing the application, don't know if you have passed the parameters to put this
Ainstance into the widget hierarchy so it gets closed.This is where breakpoint is.
A::~A() { delete ui; //Breakpoint }I created an instance on a parent window. The main window.
A* a = new A; a->show();Is this why a isn't destroyed after closing the window?
-
@JonB said in I closed a dialog, but it seems to be still running:
@MasterBlade
It sounds like yourint gid;is what you say, a global variable, not a member of yourAclass. So it has nothing to do with your class instances, and so will retain its value.Closing/re-opening a
QWidgetis not the same thing asnew/delete-ing it, so it would not reset a member variable anyway. Unless you setQt::WA_DeleteOnClose.Don't know about your breakpoint on closing the application, don't know if you have passed the parameters to put this
Ainstance into the widget hierarchy so it gets closed.This is where breakpoint is.
A::~A() { delete ui; //Breakpoint }I created an instance on a parent window. The main window.
A* a = new A; a->show();Is this why a isn't destroyed after closing the window?
@MasterBlade said in I closed a dialog, but it seems to be still running:
Is this why a isn't destroyed after closing the window?
Yes, because you don't delete it
-
@JonB said in I closed a dialog, but it seems to be still running:
@MasterBlade
It sounds like yourint gid;is what you say, a global variable, not a member of yourAclass. So it has nothing to do with your class instances, and so will retain its value.Closing/re-opening a
QWidgetis not the same thing asnew/delete-ing it, so it would not reset a member variable anyway. Unless you setQt::WA_DeleteOnClose.Don't know about your breakpoint on closing the application, don't know if you have passed the parameters to put this
Ainstance into the widget hierarchy so it gets closed.This is where breakpoint is.
A::~A() { delete ui; //Breakpoint }I created an instance on a parent window. The main window.
A* a = new A; a->show();Is this why a isn't destroyed after closing the window?
@MasterBlade said in I closed a dialog, but it seems to be still running:
I created an instance on a parent window. The main window.
A* a = new A;
a->show();No you didn't. There is no mention of the parent/main window here. In fact, given your code showing constructor
A::A(QWidget* parent)I don't even know whether you have declaredparentas optional/defaulting tonullptrlikeQWidgetdoes. Assuming it does default (else your call wouldn't compile), you have not set its parent to the main window, it's a top-level window/modeless dialog and it won't get destroyed unless you do it explicitly. -
@MasterBlade said in I closed a dialog, but it seems to be still running:
I created an instance on a parent window. The main window.
A* a = new A;
a->show();No you didn't. There is no mention of the parent/main window here. In fact, given your code showing constructor
A::A(QWidget* parent)I don't even know whether you have declaredparentas optional/defaulting tonullptrlikeQWidgetdoes. Assuming it does default (else your call wouldn't compile), you have not set its parent to the main window, it's a top-level window/modeless dialog and it won't get destroyed unless you do it explicitly.@JonB said in I closed a dialog, but it seems to be still running:
@MasterBlade said in I closed a dialog, but it seems to be still running:
I created an instance on a parent window. The main window.
A* a = new A;
a->show();No you didn't. There is no mention of the parent/main window here. In fact, given your code showing constructor
A::A(QWidget* parent)I don't even know whether you have declaredparentas optional/defaulting tonullptrlikeQWidgetdoes. Assuming it does default (else your call wouldn't compile), you have not set its parent to the main window, it's a top-level window/modeless dialog and it won't get destroyed unless you do it explicitly.Thank you. I thought closing the window would destroy it but it seems not.
So how do I destroy it? -
@JonB said in I closed a dialog, but it seems to be still running:
@MasterBlade said in I closed a dialog, but it seems to be still running:
I created an instance on a parent window. The main window.
A* a = new A;
a->show();No you didn't. There is no mention of the parent/main window here. In fact, given your code showing constructor
A::A(QWidget* parent)I don't even know whether you have declaredparentas optional/defaulting tonullptrlikeQWidgetdoes. Assuming it does default (else your call wouldn't compile), you have not set its parent to the main window, it's a top-level window/modeless dialog and it won't get destroyed unless you do it explicitly.Thank you. I thought closing the window would destroy it but it seems not.
So how do I destroy it?@MasterBlade
Either by callingdeleteLater()on it after you/the user has closed it, or by settingQt::WA_DeleteOnCloseon it, e.g.QDialog *dlg = new QDialog; dlg->setAttribute(Qt::WA_DeleteOnClose, true); // either this line... dlg->exec(); dlg->deleteLater(); // ...or this lineIf you give a
QObject, such as aQWidget, a parent then it will get deleted if/when the parent gets deleted. This works well for non-top-level objects. But in your case you did not do that: you wentnew A. You said "I created an instance on a parent window.", but you didn't pass the parent,new A(parent), so it didn't have a parent and hence would not get destroyed with the parent.One tip is that there is a
QObject::destroyedsignal on everyQObject. If you slot onto it and you don't see it being called, the object hasn't been destroyed! -
@MasterBlade
Either by callingdeleteLater()on it after you/the user has closed it, or by settingQt::WA_DeleteOnCloseon it, e.g.QDialog *dlg = new QDialog; dlg->setAttribute(Qt::WA_DeleteOnClose, true); // either this line... dlg->exec(); dlg->deleteLater(); // ...or this lineIf you give a
QObject, such as aQWidget, a parent then it will get deleted if/when the parent gets deleted. This works well for non-top-level objects. But in your case you did not do that: you wentnew A. You said "I created an instance on a parent window.", but you didn't pass the parent,new A(parent), so it didn't have a parent and hence would not get destroyed with the parent.One tip is that there is a
QObject::destroyedsignal on everyQObject. If you slot onto it and you don't see it being called, the object hasn't been destroyed!@JonB said in I closed a dialog, but it seems to be still running:
@MasterBlade
Either by callingdeleteLater()on it after you/the user has closed it, or by settingQt::WA_DeleteOnCloseon it, e.g.QDialog *dlg = new QDialog; dlg->setAttribute(Qt::WA_DeleteOnClose, true); // either this line... dlg->exec(); dlg->deleteLater(); // ...or this lineIf you give a
QObject, such as aQWidget, a parent then it will get deleted if/when the parent gets deleted. This works well for non-top-level objects. But in your case you did not do that: you wentnew A. You said "I created an instance on a parent window.", but you didn't pass the parent,new A(parent), so it didn't have a parent and hence would not get destroyed with the parent.One tip is that there is a
QObject::destroyedsignal on everyQObject. If you slot onto it and you don't see it being called, the object hasn't been destroyed!So I need to change it to
A* a = new A(this);a gets destroyed when the mainwindow is closed.
But I want to destroy a as soon as a's window is closed. How can I do that?
Shall it be likeA* a = new A(a); -
@JonB said in I closed a dialog, but it seems to be still running:
@MasterBlade
Either by callingdeleteLater()on it after you/the user has closed it, or by settingQt::WA_DeleteOnCloseon it, e.g.QDialog *dlg = new QDialog; dlg->setAttribute(Qt::WA_DeleteOnClose, true); // either this line... dlg->exec(); dlg->deleteLater(); // ...or this lineIf you give a
QObject, such as aQWidget, a parent then it will get deleted if/when the parent gets deleted. This works well for non-top-level objects. But in your case you did not do that: you wentnew A. You said "I created an instance on a parent window.", but you didn't pass the parent,new A(parent), so it didn't have a parent and hence would not get destroyed with the parent.One tip is that there is a
QObject::destroyedsignal on everyQObject. If you slot onto it and you don't see it being called, the object hasn't been destroyed!So I need to change it to
A* a = new A(this);a gets destroyed when the mainwindow is closed.
But I want to destroy a as soon as a's window is closed. How can I do that?
Shall it be likeA* a = new A(a);A* a = new A(a);Fortunately the compiler should stop you trying that. Please think about it: you can't make
a's parent bea, not to mention thatais uninitialized when you pass it.But I want to destroy a as soon as a's window is closed. How can I do that?
You saw that my code offered you a couple of ways, including:
dlg->setAttribute(Qt::WA_DeleteOnClose, true); // either this line...That looks like a suitably named flag, doesn't it? https://doc.qt.io/qt-5/qt.html#WidgetAttribute-enum
-
A* a = new A(a);Fortunately the compiler should stop you trying that. Please think about it: you can't make
a's parent bea, not to mention thatais uninitialized when you pass it.But I want to destroy a as soon as a's window is closed. How can I do that?
You saw that my code offered you a couple of ways, including:
dlg->setAttribute(Qt::WA_DeleteOnClose, true); // either this line...That looks like a suitably named flag, doesn't it? https://doc.qt.io/qt-5/qt.html#WidgetAttribute-enum
@JonB said in I closed a dialog, but it seems to be still running:
A* a = new A(a);Fortunately the compiler should stop you trying that. Please think about it: you can't make
a's parent bea, not to mention thatais uninitialized when you pass it.But I want to destroy a as soon as a's window is closed. How can I do that?
You saw that my code offered you a couple of ways, including:
dlg->setAttribute(Qt::WA_DeleteOnClose, true); // either this line...That looks like a suitably named flag, doesn't it? https://doc.qt.io/qt-5/qt.html#WidgetAttribute-enum
Thank you so much! This problem is solved!
Would you be kind to take a look at another problem I have? Looks like a compiler problem.
https://forum.qt.io/topic/114057/watchlist-disappeared-during-debugging -
@JonB said in I closed a dialog, but it seems to be still running:
A* a = new A(a);Fortunately the compiler should stop you trying that. Please think about it: you can't make
a's parent bea, not to mention thatais uninitialized when you pass it.But I want to destroy a as soon as a's window is closed. How can I do that?
You saw that my code offered you a couple of ways, including:
dlg->setAttribute(Qt::WA_DeleteOnClose, true); // either this line...That looks like a suitably named flag, doesn't it? https://doc.qt.io/qt-5/qt.html#WidgetAttribute-enum
Thank you so much! This problem is solved!
Would you be kind to take a look at another problem I have? Looks like a compiler problem.
https://forum.qt.io/topic/114057/watchlist-disappeared-during-debugging@MasterBlade
I did see that one and have no idea. It doesn't look right that it should do that! Does it happen elsewhere/on another program? Re-install Qt Creator? ;-) -
@MasterBlade
I did see that one and have no idea. It doesn't look right that it should do that! Does it happen elsewhere/on another program? Re-install Qt Creator? ;-)@JonB said in I closed a dialog, but it seems to be still running:
@MasterBlade
I did see that one and have no idea. It doesn't look right that it should do that! Does it happen elsewhere/on another program? Re-install Qt Creator? ;-)This problem appeared recently. I don't know if it's a problem of qt or some software settings.
During my test, only some functions are affected, and not always.
For some functions, watchlist disappeared the first time I press F10, but it comes back later after a switch statement. Maybe I should reinstall QtCreator.
