Question

I wanto do something like this, is it possible in python.

f = 'free'
p = 'paid'
if version is f:
      APP_VER = 'APP_FREE'
elif version is p:
      APP_VER = 'APP_PAID'

s_email = webapp2.get_app().config[APP_VER]['SUPPORT_EMAIL']

Error: UnboundLocalError: local variable 'APP_VER' referenced before assignment

Any idea!

Answer 1

if version is f:
      APP_VER = 'APP_FREE'
elif version is p:
      APP_VER = 'APP_PAID'

there is a possibility version is neither f nor p. Include an else part. Also (as @jamylak notes) use == to compare strings, not is:

if version == f:
      APP_VER = 'APP_FREE'
elif version == p:
      APP_VER = 'APP_PAID'
else:
    print 'version <{0}> unknown'.format(version)
    exit()
    # or raise an exception here

Another way (great improvement if the list of versions is longer):

app_name = {'free': 'APP_FREE',
            'paid': 'APP_PAID'} # this can be extended if needed
APP_VER = app_name.get(version)
# APP_VER is None if version unknown