Move LICENSE.django closer to the actual trumk/app/django code we are importing
(that exists in trunk/app to be part of the Google App Engine image).
LICENSE.django cannot go in trunk/app/django itself, because that directory is
maintained from the /vendor/django svn external using svn_load_dirs.pl (so
putting all the way into trunk/app/django gets it repeatedly removed).
Patch by: Todd Larsen
Review by: to-be-reviewed
"""
Common checksum routines (used in multiple localflavor/ cases, for example).
"""
__all__ = ['luhn',]
LUHN_ODD_LOOKUP = (0, 2, 4, 6, 8, 1, 3, 5, 7, 9) # sum_of_digits(index * 2)
def luhn(candidate):
"""
Checks a candidate number for validity according to the Luhn
algorithm (used in validation of, for example, credit cards).
Both numeric and string candidates are accepted.
"""
if not isinstance(candidate, basestring):
candidate = str(candidate)
try:
evens = sum([int(c) for c in candidate[-1::-2]])
odds = sum([LUHN_ODD_LOOKUP[int(c)] for c in candidate[-2::-2]])
return ((evens + odds) % 10 == 0)
except ValueError: # Raised if an int conversion fails
return False