How to restart an QApplication

Question

I need to restart my application when a button is clicked, but I'm having some problems with it. I've tried two methods:

Tried this suggestion and it indeed restarts the application, but I get a Gtk_IS_INVISIBLE (widget) error for every widget, and all of them look different in the restarted application, with a very "old" look (similar to TkInter widgets). Is there a way so solve this error? Besides this, the application works fine.
I also tried:
```
subprocess.Popen("/home/pi/pywork/pyqt/of2.py")
sys.exit(0)
```
as suggested here, but I get the following error: OSError: [Errno 13] Permission denied. Is there a way to override this denied permission?

None of them seem to work properly. Is there a way to fix any of them? Do you know an alternative method to restart the application?

Please clarify what you mean by "restart", because the two examples you give are very different. Do you actually need to create a completely *new* process? Or do you just need to create a new application object and main window within the *current* process? Or perhaps all you need to do is to create a new main window, but using the same application object? What actual problem are you trying solve? — ekhumoro, Mar 19 '16 at 21:36
I want to close the current process and start a new one. I solved the widget errors on the first suggestion by setting a style on the app, so by placing `setStyle("GTK+")`, the widget errors went away. — Diogo Magalhães, Mar 20 '16 at 13:59

score 1 · Answer 1 · edited May 23 '17 at 11:59

1

You could use QProcess.startDetached:

QProcess.startDetached("/home/pi/pywork/pyqt/of2.py")
sys.exit(0)

You also have to properly add the shebang to your python script:

#!/usr/bin/env python

edited May 23 '17 at 11:59

Community

1
1

answered Mar 20 '16 at 17:14

Daniele Pantaleone

2,657
22
33

score 1 · Answer 2 · answered Mar 20 '16 at 18:52

The second method gives an error because the file is not executable. You could fix that, but it is probably more robust to just re-run the script using the same python executable. It would also be a good idea to avoid hard-coding the script path.

Here is a simple demo script that implements all that:

import sys, os, subprocess
from PyQt4 import QtCore, QtGui

FILEPATH = os.path.abspath(__file__)

class Window(QtGui.QWidget):
    def __init__(self):
        super(Window, self).__init__()
        self.button = QtGui.QPushButton(
            'Restart [PID: %d]' % QtGui.qApp.applicationPid(), self)
        self.button.clicked.connect(self.handleButton)
        layout = QtGui.QVBoxLayout(self)
        layout.addWidget(self.button)

    def handleButton(self):
        try:
            subprocess.Popen([sys.executable, FILEPATH])
        except OSError as exception:
            print('ERROR: could not restart aplication:')
            print('  %s' % str(exception))
        else:
            QtGui.qApp.quit()

if __name__ == '__main__':

    app = QtGui.QApplication(sys.argv)
    window = Window()
    window.setGeometry(600, 400, 100, 50)
    window.show()
    sys.exit(app.exec_())

How to restart an QApplication

2 Answers2

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