I have a big gnarly function named get_start_and_stop_dates. Please rewrite it into something that still passes all the doctests but isn’t so ugly.
If you save this in a file named matt_sucks.py, you can run all the doctests like this:
$ nosetests --with-doctest matt_sucks.py
Doctest: matt_sucks.get_first_and_last_dom ... ok
Doctest: matt_sucks.get_start_and_stop_dates ... ok
Doctest: matt_sucks.stubborn_datetimeparser ... ok
----------------------------------------------------------------------
Ran 3 tests in 0.028s
OK
Here’s the code:
import simplejson
from datetime import date, datetime, timedelta
def get_start_and_stop_dates(d, s):
"""
Returns a tuple of datetime.date objects.
First checks dictionary d, then looks in the cookie s, then returns
the results of get_first_and_last_dom().
We return values from the dictionary d, even if the values exist in
simple_cookie s:
>>> d = {'start_date':'12-07-2008', 'stop_date':'12-20-2008'}
>>> import Cookie, simplejson
>>> s = Cookie.SimpleCookie()
>>> s['start_date'] = simplejson.dumps('12-08-2008')
>>> s['stop_date'] = simplejson.dumps('12-11-2008')
>>> a, b = get_start_and_stop_dates(d, s)
>>> from datetime import date
>>> isinstance(a, date) and isinstance(b, date)
True
>>> a.strftime('%m-%d-%Y'), b.strftime('%m-%d-%Y')
('12-07-2008', '12-20-2008')
If the dictionary d doesn't have values, then we get them from the
simple_cookie object s:
>>> a, b = get_start_and_stop_dates({}, s)
>>> from datetime import date
>>> isinstance(a, date) and isinstance(b, date)
True
>>> a.strftime('%m-%d-%Y'), b.strftime('%m-%d-%Y')
('12-08-2008', '12-11-2008')
We handle mix-and-match scenarios, like where one value is in d and
another is in s:
>>> s2 = Cookie.SimpleCookie()
>>> s2['stop_date'] = simplejson.dumps('2-28-1975')
>>> get_start_and_stop_dates({'start_date':'2-17-1975'}, s2)
(datetime.date(1975, 2, 17), datetime.date(1975, 2, 28))
When just one of the dates is specified, then the other will be
the first/last day of the month containing the other date:
>>> get_start_and_stop_dates({'start_date':'2-17-1975'},
... Cookie.SimpleCookie())
(datetime.date(1975, 2, 17), datetime.date(1975, 2, 28))
>>> get_start_and_stop_dates({'stop_date':'2-17-1975'},
... Cookie.SimpleCookie())
(datetime.date(1975, 2, 1), datetime.date(1975, 2, 17))
Finally, we call get_first_and_last_dom when all else fails:
>>> get_first_and_last_dom() == get_start_and_stop_dates({},
... Cookie.SimpleCookie())
True
"""
# I've revised this several times, but this is still pretty ugly.
# It probably can be divided into more functions.
# These are the last-resort values, holding the first and last days
# of the current month.
first, last = get_first_and_last_dom()
# These are the dateformats that the dates will be in.
dateformats = ['%m-%d-%Y', '%Y-%m-%d', '%Y-%m-%d %H:%M:%S']
start_date = stop_date = None
# Figure out the start_date first.
if 'start_date' in d and d['start_date']:
start_date = stubborn_datetimeparser(d['start_date'],
dateformats).date()
elif s.has_key('start_date') and s['start_date'].value:
start_date = stubborn_datetimeparser(simplejson.loads(s['start_date'].value),
dateformats).date()
# Now repeat the process for stop_date.
# TODO: pull this redundancy into a single function and call it
# twice.
if 'stop_date' in d and d['stop_date']:
stop_date = stubborn_datetimeparser(d['stop_date'],
dateformats).date()
elif s.has_key('stop_date') and s['stop_date'].value:
stop_date = stubborn_datetimeparser(simplejson.loads(s['stop_date'].value),
dateformats).date()
# Now figure out what to return. Remember, if we found one date,
# but not the other, then we return the first/last date of that month,
# not the current month.
if not start_date and not stop_date:
return first, last
elif start_date and stop_date:
return start_date, stop_date
elif start_date and not stop_date:
a, b = get_first_and_last_dom(start_date)
return start_date, b
elif not start_date and stop_date:
a, b = get_first_and_last_dom(stop_date)
return a, stop_date
def get_first_and_last_dom(dt="today"):
"""
Return a tuple of datetime.date objects with the first and last day of the
month holding dt, which defaults to today.
>>> first, last = get_first_and_last_dom(datetime(2008, 12, 6))
>>> first == datetime(2008, 12, 1).date()
True
>>> last == datetime(2008, 12, 31).date()
True
>>> first, last = get_first_and_last_dom(datetime(2008, 11, 30))
>>> first == datetime(2008, 11, 1).date()
True
>>> last == datetime(2008, 11, 30).date()
True
"""
if dt == "today":
dt = datetime.now()
# We have to be a little careful figuring out the last date.
if dt.month < 12:
last_day = (datetime(dt.year, dt.month+1, 1) - timedelta(days=1)).date()
else:
last_day = (datetime(dt.year+1, 1, 1) - timedelta(days=1)).date()
first_day = datetime(dt.year, dt.month, 1).date()
return first_day, last_day
def stubborn_datetimeparser(s, dateformats):
"""
Keep trying to parse s into a datetime object until we succeed or
run out of dateformats.
When the first format works, we immediately return:
>>> dateformats = ['%Y-%m-%d', '%m-%d-%Y', '%m-%d-%Y %H:%M']
>>> stubborn_datetimeparser('12-1-2008', dateformats)
datetime.datetime(2008, 12, 1, 0, 0)
Otherwise, we keep trying until we parse it:
>>> stubborn_datetimeparser('12-1-2008', dateformats)
datetime.datetime(2008, 12, 1, 0, 0)
>>> stubborn_datetimeparser('12-1-2008 15:47', dateformats)
datetime.datetime(2008, 12, 1, 15, 47)
or we run out of formats, and raise a ValueError:
>>> stubborn_datetimeparser('12/1/2008', dateformats)
Traceback (most recent call last):
...
ValueError: I couldn't parse '12/1/2008' with any of my formats!
"""
for datefmt in dateformats:
try:
return datetime.strptime(s, datefmt)
except ValueError:
pass
# This else matches the for datefmt in dateformats loop. It means
# that we didn't break out of the loop early.
else:
raise ValueError("I couldn't parse '%s' with any of my formats!" % s)
Now get to work!
