app/django/utils/checksums.py
author Sverre Rabbelier <srabbelier@gmail.com>
Sat, 13 Dec 2008 13:28:01 +0000
changeset 736 c70d56182ce2
parent 54 03e267d67478
permissions -rw-r--r--
No override needed in notifications.py The only downside is that the ?s=0 parameter will still be appended but is not handled in list(). The right solution would be to update list() so that it does say "Message Sent" or such, to give the user an indication that their message was sent succesfully. Patch by: Sverre Rabbelier

"""
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