Serializing / Unserializing datetime

[Gerard Flanagan]

Brendan wrote:
> Thanks John.   I've discovered that datetime.strptime will be available
> in 2.5, (http://docs.python.org/dev/whatsnew/modules.html) but your
> example will work in the meantime.
>
> BJ

I don't think it's what you want but I had the following on file - it
uses time.strptime() which I didn't know there was a problem with.  Not
tested beyond what you see.

--------------------------------------------------------------------------------
import time
import datetime

DDMMYY = ['%d %m %Y', '%d %m %y', '%d/%m/%Y', '%d/%m/%y', '%d-%m-%Y',
'%d-%m-%y' ]

def yearmonthday(datestring, fmts=DDMMYY):
    ymd = None
    for f in fmts:
        try:
            ymd = time.strptime( datestring, f )
            break
        except ValueError:
            continue
    if ymd is None:
        raise ValueError
    return ymd[0], ymd[1], ymd[2]

def is_valid_date(datestring, fmts=DDMMYY):
    try:
        yearmonthday(datestring, fmts)
        return True
    except ValueError:
        return False

def string_to_date(datestring, fmts=DDMMYY):
    return datetime.date( *yearmonthday(datestring, fmts) )

assert string_to_date( '1/2/01', DDMMYY) == datetime.date(2001,2,1)
assert string_to_date( '1 2 01', DDMMYY) == datetime.date(2001,2,1)
assert string_to_date( '01/02/01', DDMMYY) == datetime.date(2001,2,1)
assert string_to_date( '1/02/2001', DDMMYY) == datetime.date(2001,2,1)
assert string_to_date( '29/02/2008', DDMMYY) ==
datetime.date(2008,2,29)
assert string_to_date( '01/2/99', DDMMYY) == datetime.date(1999,2,1)

for d in [ '', '32/1/01', '01/13/01', '29/2/07', '1/2', 'abcdef' ]:
    assert not is_valid_date(d, DDMMYY)
------------------------------------------------------------------------------------

Gerard