app/django/utils/checksums.py
author Sverre Rabbelier <sverre@rabbelier.nl>
Sat, 09 May 2009 15:28:26 +0200
changeset 2303 11cf7f2cc4ff
parent 54 03e267d67478
permissions -rw-r--r--
[PATCH] Remove __init__.py from app, as app is not a module From 6916391964ed3b48021351d3a9ea7a7bc836a373 Mon Sep 17 00:00:00 2001 Date: Sat, 9 May 2009 15:19:04 +0200 --- scripts/build.sh | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) delete mode 100644 app/__init__.py

"""
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