A key_name controller module to collect all of the name...() functions that
compose Model entity key names, plus some minor changes to other controller
modules to illustrate the proposed use.
Patch by: Todd Larsen
Review by: Pawel Solyga
Review URL: http://codereviews.googleopensourceprograms.com/804
Review URL: http://codereviews.googleopensourceprograms.com/804
"""
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