[Qt-4.1.4, sip-4.4.5, PyQt-4.0.1, Python-2.4.3, MSVC-7.1] Hi all,
I've been facing a random crash in my app for sometime, and i've got it down to a simple test program. Run the attached script, click "Click Me" and close the newly opened window, and it crashes! I used debug builds and poked around the code, and here's why i think its crashing... The crash happens when a top-level window is closed, and all python references to the window are lost in the 'closeEvent' method. When a window is closed using the close button at the right top of the window, the Qt function "QWidgetPrivate::close_helper(mode)" gets called with "mode == CloseWithSpontaneousEvent". This function is there in src/gui/kernel/qwidget.cpp line 4609. In this function, close event is sent to the widget if mode is CloseWithSpontaneousEvent, as in this case. By the time, the close event is handled by the widget, the widget is already deleted because of python's gc. The Qt code seems to check for this case using tests like "that.isNull()". But on line 4642, the check for null is not performed and the app crashes at that point. So this looks like it is a bug in Qt itself. But is there someway PyQt can workaround this bug? regards [sreeram;]
import sys from PyQt4 import QtCore, QtGui window_list = [] class MyWindow( QtGui.QWidget ) : def __init__( self ) : QtGui.QWidget.__init__( self ) self.label = QtGui.QLabel( 'Hi There!' ) layout = QtGui.QVBoxLayout() layout.addWidget( self.label ) self.setLayout( layout ) window_list.append( self ) def closeEvent( self, ev ) : window_list.remove( self ) QtGui.QWidget.closeEvent( self, ev ) class MainWindow( QtGui.QWidget ) : def __init__( self ) : QtGui.QWidget.__init__( self ) self.button = QtGui.QPushButton( 'Click Me!' ) layout = QtGui.QVBoxLayout() layout.addWidget( self.button ) self.setLayout( layout ) self.connect( self.button, QtCore.SIGNAL('clicked()'), self._onClick ) def _onClick( self ) : w = MyWindow() w.show() def main() : app = QtGui.QApplication( sys.argv ) w = MainWindow() w.show() app.exec_() if __name__ == '__main__' : main()
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