pyqt4 Main window crashes after second window closes - python-3.x

Question

I've got this simple program. Its has a button and when you press it a second window will come up.
from PyQt4.QtCore import *
from PyQt4.QtGui import *
import sys
import urllib.request
class second_window(QDialog):
def __init__(self, parent=None):
QDialog.__init__(self)
super(second_window, self).__init__(parent)
layout = QVBoxLayout()
button = QPushButton("close")
button.clicked.connect(self.button_clicked)
layout.addWidget(button)
self.setLayout(layout)
def button_clicked(self):
self.close()
class Main_window(QDialog):
def __init__(self):
QDialog.__init__(self)
layout = QVBoxLayout()
button = QPushButton("Second Window")
self.sec_window = second_window(self)
layout.addWidget(button)
button.clicked.connect(self.button_clicked)
self.setLayout(layout)
def button_clicked(self):
self.sec_window.exec_()
if __name__ == "__main__":
app = QApplication(sys.argv)
dl = window()
dl.show()
app.exec()
But sometimes if you close the Main_window just after you close the second_window it crashes and I get a message saying "Python.exe has stopped working".
can anyone help?

Answer 1

First Solution: Change self.sec_window = second_window(self) to self.sec_window = second_window() since it will not be necessary to clean because there is no relationship between second_window and Main_window. As the following code shows
from PyQt4.QtCore import *
from PyQt4.QtGui import *
import sys
class second_window(QDialog):
def __init__(self, parent=None):
QDialog.__init__(self)
super(second_window, self).__init__(parent)
layout = QVBoxLayout()
button = QPushButton("close")
button.clicked.connect(self.button_clicked)
layout.addWidget(button)
self.setLayout(layout)
def button_clicked(self):
self.close()
class Main_window(QDialog):
def __init__(self):
QDialog.__init__(self)
layout = QVBoxLayout()
button = QPushButton("Second Window")
self.sec_window = second_window()
layout.addWidget(button)
button.clicked.connect(self.button_clicked)
self.setLayout(layout)
def button_clicked(self):
self.sec_window.exec_()
if __name__ == "__main__":
app = QApplication(sys.argv)
dl = Main_window()
dl.show()
app.exec()
Second Solution: Add self.sec_window.deleteLater() on closeEvent(self, event) to be able to delete second_window
from PyQt4.QtCore import *
from PyQt4.QtGui import *
import sys
class second_window(QDialog):
def __init__(self, parent=None):
QDialog.__init__(self)
super(second_window, self).__init__(parent)
layout = QVBoxLayout()
button = QPushButton("close")
button.clicked.connect(self.button_clicked)
layout.addWidget(button)
self.setLayout(layout)
def button_clicked(self):
self.close()
class Main_window(QDialog):
def __init__(self):
QDialog.__init__(self)
layout = QVBoxLayout()
button = QPushButton("Second Window")
self.sec_window = second_window(self)
layout.addWidget(button)
button.clicked.connect(self.button_clicked)
self.setLayout(layout)
def button_clicked(self):
self.sec_window.exec_()
def closeEvent(self, event):
self.sec_window.deleteLater()
super().closeEvent(event)
if __name__ == "__main__":
app = QApplication(sys.argv)
dl = Main_window()
dl.show()
app.exec()