Hi Mike, I agree with your opion. Actually, I did backtrace. The message showed like "~qobject, qobject.cpp can not find." I guess that the pyqt try to delete an deleted object.
If you have other ideas, please let me know. Thanks! Jian On Fri, Jul 29, 2011 at 7:44 PM, Mike Ramirez <gufym...@gmail.com> wrote: > On Friday, July 29, 2011 04:20:27 PM Algis Kabaila wrote: > > On Sat, 30 Jul 2011 08:18:58 AM Jian Ma wrote: > > > Hi all, > > > > > > I created a QMenu object in a class. When I created it with menu = > > > QMenu(self) and run the program, it sometimes got the "segmentation > > > fault" after exit the program. When I created the object with menu = > > > QMenu(), it didn't get this problem. I guess the reason is about the > > > QMenu object ownership. In one case, the object is owned by PyQt. In > > > other case, it is owned by Qt. I am not sure my guess. Can someone give > > > some explanation? Below is some code segment. > > > > > > class DnDMenuListWidget(QListWidget): > > > ... > > > ... > > > > > > def dropEvent(self, event): > > > ... > > > ... > > > menu = QMenu(self) # using QMenu(self) > > > # menu = QMenu() # using QMenu() > > > ... > > > ... > > > > > > Thanks! > > > > In Python in a class instantiation the instance name is automatically > > passed in a parameter, usually in a named variable "self", so if QMenu is > > a method of a class, a varible named "self" needs to be specified, hence > > QMenu(self). > > > > If Qmenu is used as a function outside of a class creation, the "self" > > argument is not required, so for functions, hence QMenu(). > > > > For further information read up on class creation of Python (and class > > instantiation and class instances). > > > > Good luck, > > OldAl. > > _______________________________________________ > > You're right about this stuff for python, but wrong about in this usage. In > this case self is the parent object that owns the QMenu() child. It's not a > method of the parent object, but an attribute. > > i.e. > > class MainWindow(QMainWindow): > # your explanation > def __init__(self, parent=None): > # his usage. > self.menu = QMenu(self) > > Using QMenu() without self, just sets the menu's parent to None at > instination. > > The problem is appears to bein the destruction of the parent. I'm not sure. > It > does sounds like the parent is being deystroyed before the child (like the > discussion on the list a few months ago). I can't remember the subject or > the > fix, but I think the fix was to set the child objects parent to None before > it > the parent was destroyed. This is an _I Think_. Others who participated > in > that convo would be better at answering it. > > Mike > > -- > They are called computers simply because computation is the only > significant > job that has so far been given to them. > _______________________________________________ > PyQt mailing list PyQt@riverbankcomputing.com > http://www.riverbankcomputing.com/mailman/listinfo/pyqt >
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