Traceback error when exiting a Python2.7 + PyQt4 program?

Question

Python

I wrote a lot of plugins for 3D packages in Python + PyQt and they all ran inside the same packages for which they were written. And so I decided to write just a standalone application on the same bundle. Took the simplest example straight from the documentation:

import sys
from PyQt4 import QtGui

def main():
    app = QtGui.QApplication(sys.argv)
    w = QtGui.QWidget()
    w.resize(250, 150)
    w.move(300, 300)
    w.setWindowTitle('Simple')
    w.show()
    sys.exit(app.exec_())

if __name__ == '__main__':
    main()

Fulfilled ... A window appeared, rejoiced and closed it. And in python output I immediately saw an error:

Traceback (most recent call last):
  File "D:\Temp\test_qt3.py", line 14, in <module>
    main()
  File "D:\Temp\test_qt3.py", line 11, in main
    sys.exit(app.exec_())
SystemExit: 0

Somehow it scares me that the application from the documentation gives an error when exiting. I also tried more complex examples from them - and all exits end with such an error. Of course, I can find fault and such an output is standard for all PyQt applications - but the error annoys me and I don’t like warnings to even be in the program, not to mention errors ...
In general, the question is this - what is wrong in the exit from program and why this error is generated and how to fix it?

Answer 1

It's not a mistake. This is the default behavior of sys.exit(): it throws a SystemExit exception. Read more in the documentation.