app/django/utils/checksums.py
author Pawel Solyga <Pawel.Solyga@gmail.com>
Tue, 14 Oct 2008 16:10:07 +0000
changeset 324 05e21c089be6
parent 54 03e267d67478
permissions -rw-r--r--
Add missing import in soc/views/site/sponsor/list.py which caused exception when app was deployed and first site you visited was "List Site Sponsors". Update files according to recent django update and django backwards incompatibility (for example newforms is changed to forms). Patch by: Pawel Solyga 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