Using sys.exit() with app.exec_ in pyqt

Question

Can anyone explain the relative merits of using sys.exit(app.exec_()) rather than the simpler app.exec_() to start a GUI in PyQt?

I am new to PyQt and have seen both examples.

Answer 1

When Unix-style applications exit, they return a number to their parent process called a 'status code' or 'exit status'. 0 is used to indicate success; anything non-zero is a failure. (There's been some attempt to standardise the meaning of error codes, but it's still generally left up to each program.)

app.exec_() runs your main loop, and returns a status code when it exits. sys.exit(n) quits your application and returns n to the parent process (normally your shell). So the difference is, the longer version passes on the status code when your program exits. It's better to use sys.exit(app.exec_()) because then other parts of the system can detect when your program exited due to an error.