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Rewrite my ugly code

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:

Now get to work!

Posted in Programming, Python.

By matt

December 6, 2008

Comments

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Password Recovery 02/03/2009 01:15 AM 1 point
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Man I'd help you out but it looks way too complicated for me. I am a php newb still learning from guys like you. Keep up the good work.

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Doug Hellmann 12/06/2008 08:43 PM 2 points
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Here's my stab at it: http://blog.doughellmann.com/2...

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Matt Wilson 12/06/2008 08:54 PM 1 point
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That calendar.monthrange trick is nice. Allows me to forget about nonsense like leap year and special logic for December.

I read somewhere that every big python app ends up building a crappier version of what's already in the standard library. I'm happy to see I've reached that point :)

Thanks for the help!

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Doug Hellmann 12/06/2008 08:58 PM 1 point
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I like that quote! And thanks, this was a fun exercise. I've been sick for a couple of days, so I haven't had my own ugly code to stare at for a while. :-)

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Mike Pirnat 12/06/2008 08:11 PM 2 points
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Actually now that I look at the rest of your code, I think dateutil has the strong possibility of making you very happy indeed.

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Matt Wilson 12/06/2008 07:44 PM 1 point
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Thanks Mike -- besides helping with parsing, what else can dateutil
help with? I remember you showed a bunch of neat recurrence trickery
as well. I think I should read all the docs.

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Mike Pirnat 12/07/2008 09:37 AM 1 point
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The highlights are:
* parsing
* timezones
* recurrence
* relative deltas

The docs are quite good, so definitely worth your time to take a peek at. There's also my presentation from PyCon 2007 if you want the quick tour with some examples (beware Gilbert & Sullivan spoilers).

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Doug Hellmann 12/06/2008 08:10 PM 2 points
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The standard library module "calendar" contains the function monthrange(), which will give you the numerical day of the first and last days of the month. The last day of the month in get_first_and_last_dom() becomes last_day = datetime.date(dt.year, dt.month, calendar.monthrange(dt.year,dt.month)[1])

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Matt Wilson 12/06/2008 07:42 PM 1 point
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Thanks Doug! I'm going to read up on the calendar module now. I bet
there is a lot of code I can streamline now.

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Mike Pirnat 12/06/2008 07:37 PM 2 points
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It's not for the function you're wanting help with, but dateutil would make much shorter work of your date parsing issues.

My typical usage for parsing date strings is (in a nutshell):

from dateutil.parser import parse as parse_date
dt = parse_date(some_date_string)

You can add your own formats to it if you need to do crazy stuff.

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