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app/django/utils/checksums.py
author Sverre Rabbelier <srabbelier@gmail.com>
Sat, 06 Dec 2008 11:53:26 +0000
changeset 675 14958011dceb
parent 54 03e267d67478
permissions -rw-r--r--
Use key().name() instead of link_id This is now possible because key_name is constructed purely from the key fields of an entity. It is not sufficient to use just link_id, that works only for single-scoped entities (e.g., those that either do not have a scope, or that have a scope which itself does not have a scope). It would break if there was an entity that has a scoped scope (it would only include the scope's link_id in the url, which made it impossible to look up the scope as we missed the link_id of the scope's scope). Patch by: Sverre Rabbelier
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03e267d67478 Major reorganization of the soc svn repo, to merge into a single App Engine
Todd Larsen <tlarsen@google.com>
parents:
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"""
03e267d67478 Major reorganization of the soc svn repo, to merge into a single App Engine
Todd Larsen <tlarsen@google.com>
parents:
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Common checksum routines (used in multiple localflavor/ cases, for example).
03e267d67478 Major reorganization of the soc svn repo, to merge into a single App Engine
Todd Larsen <tlarsen@google.com>
parents:
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     3
 
"""
03e267d67478 Major reorganization of the soc svn repo, to merge into a single App Engine
Todd Larsen <tlarsen@google.com>
parents:
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03e267d67478
Major reorganization of the soc svn repo, to merge into a single App Engine



Todd Larsen <tlarsen@google.com>


parents: 

diff
changeset




     5


__all__ = ['luhn',]













03e267d67478
Major reorganization of the soc svn repo, to merge into a single App Engine



Todd Larsen <tlarsen@google.com>


parents: 

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03e267d67478
Major reorganization of the soc svn repo, to merge into a single App Engine



Todd Larsen <tlarsen@google.com>


parents: 

diff
changeset




     7


LUHN_ODD_LOOKUP = (0, 2, 4, 6, 8, 1, 3, 5, 7, 9) # sum_of_digits(index * 2)













03e267d67478
Major reorganization of the soc svn repo, to merge into a single App Engine



Todd Larsen <tlarsen@google.com>


parents: 

diff
changeset




     8














03e267d67478
Major reorganization of the soc svn repo, to merge into a single App Engine



Todd Larsen <tlarsen@google.com>


parents: 

diff
changeset




     9


def luhn(candidate):













03e267d67478
Major reorganization of the soc svn repo, to merge into a single App Engine



Todd Larsen <tlarsen@google.com>


parents: 

diff
changeset




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    """













03e267d67478
Major reorganization of the soc svn repo, to merge into a single App Engine



Todd Larsen <tlarsen@google.com>


parents: 

diff
changeset




    11


    Checks a candidate number for validity according to the Luhn













03e267d67478
Major reorganization of the soc svn repo, to merge into a single App Engine



Todd Larsen <tlarsen@google.com>


parents: 

diff
changeset




    12


    algorithm (used in validation of, for example, credit cards).













03e267d67478
Major reorganization of the soc svn repo, to merge into a single App Engine



Todd Larsen <tlarsen@google.com>


parents: 

diff
changeset




    13


    Both numeric and string candidates are accepted.













03e267d67478
Major reorganization of the soc svn repo, to merge into a single App Engine



Todd Larsen <tlarsen@google.com>


parents: 

diff
changeset




    14


    """













03e267d67478
Major reorganization of the soc svn repo, to merge into a single App Engine



Todd Larsen <tlarsen@google.com>


parents: 

diff
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    15


    if not isinstance(candidate, basestring):













03e267d67478
Major reorganization of the soc svn repo, to merge into a single App Engine



Todd Larsen <tlarsen@google.com>


parents: 

diff
changeset




    16


        candidate = str(candidate)













03e267d67478
Major reorganization of the soc svn repo, to merge into a single App Engine



Todd Larsen <tlarsen@google.com>


parents: 

diff
changeset




    17


    try:













03e267d67478
Major reorganization of the soc svn repo, to merge into a single App Engine



Todd Larsen <tlarsen@google.com>


parents: 

diff
changeset




    18


        evens = sum([int(c) for c in candidate[-1::-2]])













03e267d67478
Major reorganization of the soc svn repo, to merge into a single App Engine



Todd Larsen <tlarsen@google.com>


parents: 

diff
changeset




    19


        odds = sum([LUHN_ODD_LOOKUP[int(c)] for c in candidate[-2::-2]])













03e267d67478
Major reorganization of the soc svn repo, to merge into a single App Engine



Todd Larsen <tlarsen@google.com>


parents: 

diff
changeset




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        return ((evens + odds) % 10 == 0)













03e267d67478
Major reorganization of the soc svn repo, to merge into a single App Engine



Todd Larsen <tlarsen@google.com>


parents: 

diff
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    except ValueError:  # Raised if an int conversion fails













03e267d67478
Major reorganization of the soc svn repo, to merge into a single App Engine



Todd Larsen <tlarsen@google.com>


parents: 

diff
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    22


        return False















py_tasks_melange