Correctly exiting an app

drscheme

I have an app that runs in a while true loop. I want to exit the app correctly. How can I do this?

On a typical console app I'd use a "try ... except keyboardinterrupt" construct but this doesn't work in my app.

Any suggestions?

Regards

Phuket2

I am a beginner, but I will try to help

Not sure what you are looking for. To answer correctly I think you need to give more context of your app. But the below code prints something then exits first time through the loop. Not sure it helps or not. If not, I think better to rewrite your question and include some code.

import contacts
import sys

my_contacts = contacts.get_all_people()
for person in my_contacts:
	print dir(person)
	sys.exit(0)

JonB

one option is to use ui, and show a button, which sets a global upon key press, which your while true loop checks for.

you can press the x button in the ui, which throws a keyboardinterrupt, but pythonista will not let you catch that exception.

ccc

The most readable way to end an infinite loop is to break out of the loop when some condition is met.

# top_of_the_minute: loop forever until seconds is zero
import datetime
print('Waiting {}...'.format(datetime.datetime.now().second))
while True:  # break out of the infinite loop when seconds is zero
    if not datetime.datetime.now().second:
        break  # or exit('Done.') or quit('Done.') or raise SystemExit('Done.') or sys.exit('Done.')
print('Done.')

I often use sys.exit() as mentioned by @Phukett2 above but raise SystemExit or exit([text or number]) or quit([text or number]) work just as well and do not require an import.

See http://stackoverflow.com/questions/19747371/python-exit-commands-why-so-many-and-when-should-each-be-used

break is best but raise SystemExit('Done.') works well too.