app/django/utils/checksums.py
author Sverre Rabbelier <srabbelier@gmail.com>
Sun, 01 Feb 2009 22:48:48 +0000
changeset 1166 558bd62ee9d4
parent 54 03e267d67478
permissions -rw-r--r--
Fix get args construction when there are multiple lists on the page It is now possible to go back and forward through the liast, and specify the limit (both offset and limit can be done per list). The JS driving the list boxes is buggy, if visiting an url like: http://localhost:8080/notification/list?limit_0=10 And then change the limit in the second checkbox, it directs to: http://localhost:8080/notification/list?limit_1=25 Whereas it should redirect to: http://localhost:8080/notification/list?limit_0=10&limit_1=25 The logic _does_ work properly when the limit of the changed list is already present in the url. 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