Comparing a string to multiple items in Python

Question

I\'m trying to compare a string called facility to multiple possible strings to test if it is valid. The valid strings are:

auth, authpriv, daem         


        

Answer 1

Unless your list of strings gets hideously long, something like this is probably best:

accepted_strings = ['auth', 'authpriv', 'daemon'] # etc etc 

if facility in accepted_strings:
    do_stuff()

Answer 2

To efficiently check if a string matches one of many, use this:

allowed = set(('a', 'b', 'c'))
if foo in allowed:
    bar()

set()s are hashed, unordered collections of items optimized for determining whether a given item is in them.

Answer 3

If, OTOH, your list of strings is indeed hideously long, use a set:

accepted_strings = {'auth', 'authpriv', 'daemon'}

if facility in accepted_strings:
    do_stuff()

Testing for containment in a set is O(1) on average.