Issue 1100942: Add datetime.time.strptime and datetime.date.strptime (original) (raw)
Created on 2005-01-12 14:53 by josh-sf, last changed 2022-04-11 14:56 by admin.
Messages (48)
Author: Josh (josh-sf)
Date: 2005-01-12 14:53
Alllow creating new datetime objects by parsing date strings.
datetime already has strftime, so adding strptime is logical.
The new constructor is equivalent to datetime(*(time.strptime(date_string, format)[0:6])).
Patch includes documentation and unit test.
Author: Alan Green (alanvgreen)
Date: 2005-01-25 12:05
Logged In: YES user_id=1174944
This patch will be welcomed by all of that have had to write "datetime(*(time.strptime(date_string, format)[0:6]))".
I don't understand the C API well enough to check if reference counts are handled properly, but otherwise the implementation looks straight forward.
Documentation looks good and the test passes on my machine.
Two suggestions:
In the time module, the strptime() function's format parameter is optional. For consistency's sake, I'd expect datetime.strptime()'s format parameter also to be optional. (On the other hand, the default value for the format is not very useful.)
Since strftime is supported by datetime.time, datetime.date and datetime.datetime, I'd also expect strptime to be supported by all three classes. Could you add that now, or would it be better to do it as a separate patch?
Author: Josh (josh-sf)
Date: 2005-02-02 00:50
Logged In: YES user_id=1194964
Regarding support by datetime.time and datetime.date, if a date component or a time component is specified, respectively, do you think that we should raise an exception? or should we just ignore it?
Author: Josh (josh-sf)
Date: 2005-02-17 17:15
Logged In: YES user_id=1194964
The first patch has been applied, now just the second needs to be. (strptime2.diff).
That adds support for date and time as well as datetime, as per alanvgreen's suggestion.
Author: Björn Lindqvist (sonderblade)
Date: 2007-06-05 20:44
The patch doesn't apply cleanly anymore, although that was easy to fix. With the patch, I also get a few implicit declaration warnings and a few conflicting type errors. Rearranging the order of the functions solve that. Fixing that makes the code compile. The two new methods seem to work correct, although there should be unit tests.
Author: Daniel Diniz (ajaksu2) * 
Date: 2009-02-14 19:08
Patch needs updating.
Author: Amaury Forgeot d'Arc (amaury.forgeotdarc) * 
Date: 2009-06-23 23:18
Here is an updated patch, with tests.
The only thing that bugs me is the name of the method: date.strptime() seems a bit odd, given that it cannot accept a time part... OTOH 'strptime' refers to the format specification: %Y-%m-%d
Author: Alexander Belopolsky (Alexander.Belopolsky)
Date: 2010-04-20 16:02
I am +1 for adding these features and I have only one comment on the code:
It is documented in time.strptime() documentation that """ The default values used to fill in any missing data when more accurate values cannot be inferred are (1900, 1, 1, 0, 0, 0, 0, 1, -1). """ http://docs.python.org/dev/py3k/library/time.html#time.strptime
and "datetime.strptime(date_string, format) is equivalent to datetime(*(time.strptime(date_string, format)[0:6]))." according to datetime module documentation.
Thus, datetime.strptime("", "") returning datetime.datetime(1900, 1, 1, 0, 0) is not an implementation detail and there is no need to compute it in time_strptime.
Author: Alexander Belopolsky (Alexander.Belopolsky)
Date: 2010-04-20 16:12
BTW, it does not bother me that "date.strptime() seems a bit odd, given that it cannot accept a time part." To me "time" in strptime means time specification that may include date, time or even just month. If parsed specification does not fit in date (includes time component), date.strptime fails. There is nothing wrong with it. An alternative would be to make {date,time}.strptime() promiscuous and just drop unneeded components, but that would make these functions less useful because such behavior is simply datetime.strptime(..).{date,time}().
Author: Alexander Belopolsky (belopolsky) *
Date: 2010-05-31 19:23
Does this need to be brought up on python-dev for acceptance?
Author: Mark Dickinson (mark.dickinson) *
Date: 2010-05-31 19:45
This doesn't appear to be at all controversial; I don't think it's necessary to consult python-dev. (I haven't looked at the patch, though.)
Author: Alexander Belopolsky (belopolsky) *
Date: 2010-06-09 15:17
I have updated Amaury's patch for py3k. I simplified the test for default date values and fixed a documentation nit. (Time fileds are [4:7], not [4:6]). The result is attached as .diff.
Note that date.strptime accepts some time specs and time.strptime accepts some date specs:
time.strptime('1900', '%Y') datetime.time(0, 0) date.strptime('00', '%H') datetime.date(1900, 1, 1)
This matches the proposed documentation, but I am not sure is desirable.
I am about +0 for making the test more robust by scanning the format string and rejecting date format codes in time.strptime and time format codes in date. This will also allow better diagnostic messages. For example, instead of
date.strptime('01', '%M') Traceback (most recent call last): .. ValueError: date.strptime value cannot have a time part
we can produce "'%M' is not valid in date format specification."
Author: Alexander Belopolsky (belopolsky) *
Date: 2010-08-18 16:39
Is anyone still interested in moving this forward?
Author: Alexander Belopolsky (belopolsky) *
Date: 2011-01-11 15:43
New patch needed to address the issue of time.strftime() accepting %Y when year is 1900 and other similar oddities. See above. Also a patch for datetime.py is needed.
Author: Alexander Belopolsky (belopolsky) *
Date: 2012-06-13 21:44
Bumping priority to get this in before beta.
Author: Juarez Bochi (Juarez.Bochi)
Date: 2012-07-19 22:00
I have updated the patches since they were not applying cleanly and included a pure Python implementation that was missing.
It has the same issues that were mentioned on .
Do you have any suggestions? I'm planning to block the formats that are not allowed and raise Exceptions like suggested before:
date.strptime('01', '%M') ... "'%M' is not valid in date format specification."
Author: Juarez Bochi (Juarez.Bochi)
Date: 2012-07-20 09:09
I've updated my patch with the tests for datetime.time.strptime that were missing and also its pure Python implementation.
The previous diff also had some issues that I've fixed now: duplicated datetime.strptime method definition in c and the pure python docstring state that date.strpdate was a method and not a constructor.
Author: Juarez Bochi (Juarez.Bochi)
Date: 2012-07-20 09:19
Sorry. I updated my patch again to fix the exception message for time.strptime in the pure Python version.
Author: Juarez Bochi (Juarez.Bochi)
Date: 2012-07-20 14:18
I've updated the patch based on ezio.melotti and berkerpeksag reviews (thanks).
It's still missing the modifications proposed on .
Author: Mark Lawrence (BreamoreBoy) *
Date: 2012-11-04 02:46
Could someone please review this with a view to getting the patch into the 3.4 code base, thanks.
Author: Alexander Belopolsky (belopolsky) *
Date: 2012-11-04 03:01
Juarez,
Are you planning to implement format validation as you described in ? Without that, date.strptime() is not very useful because it is almost equivalent to datetime.strptime().date().
Author: Berker Peksag (berker.peksag) *
Date: 2013-02-18 19:25
New patch attached.
Changes:
- Addressed . I will update the C code if this implementation is correct.
- Added more tests
- Converted classmethods to staticmethods
- Removed doctests
- Updated documentation
Author: Sean Reifschneider (jafo) *
Date: 2013-03-19 01:08
I've tried to test this but v4 doesn't apply cleanly after pure2 is applied, and v4 doesn't include enough to test it (applying v4 only causes test failures).
I reviewed v4 and it looks fine in general. I do see that there are changes in it unrelated to this issue, but they are PEP8 changes so I'm not objecting, but ideally that would be split out into a separate patch.
I think that this code will incorrectly detect something like '%s %%wall clock' as a date spec because it contains '%w', but strptime would consider that '%' followed by the string 'wall'. A subtle edge case, but worth considering. Maybe it needs to strip out %% first then look for the % sequences? Or perhaps just do the conversion and if the Y/M/D fields are set in then decide that it included a date spec, or if the HMS are set then say that it has the time spec included?
Author: Julian Gindi (Julian.Gindi) *
Date: 2013-12-18 05:05
I'm interested in taking over and finishing whatever needs to be completed to move this forward. What else needs to be done? It looks like improved tests are needed, but are there any changes needed to the implementation code?
Author: Vajrasky Kok (vajrasky) *
Date: 2013-12-18 06:24
Julian, You need to update the patch from Juarez Bochi and Berker Peksag to the tip.
Author: Maciej Szulik (maciej.szulik) *
Date: 2013-12-18 07:54
Julian I'm almost done with this issue. I just need to polish that a little bit and I'll provide working patch withing few hours. Sorry for not writing about that later, but I'm just starting with this and I had some time figuring it out.
Author: Julian Gindi (Julian.Gindi) *
Date: 2013-12-18 14:17
Maciej, cool! I just wanted to move this patch forward because A) it seemed inactive and B) I would love to see this feature make it in :) I guess that means there is nothing that I need to do. Looking forward to this one, good work!
Author: Maciej Szulik (maciej.szulik) *
Date: 2013-12-20 23:28
I'm attaching merged and fixed patch (issue1100942_full.patch). Though during testing I found one issue with the patch: during checking for time part in date class I'm using (in _datetimemodule.c->date_strptime) DATE_GET_HOUR etc, but when given time parts are 0's then the test fails. Should I leave the patch as is, because possibility for 0's is very low or should I check the format string for time parts existence? Any further advice is appreciated.
Author: Maciej Szulik (maciej.szulik) *
Date: 2014-04-03 21:39
I've just checked the patch still applies to current HEAD. What about the question regarding 0's in date.strptime(...) I asked in previous comment? I'd like to move this issue forward now when 3.4 is released.
Author: Alexander Belopolsky (belopolsky) *
Date: 2014-04-03 21:53
Is this documentation still valid?
+.. staticmethod:: date.strptime(date_string, format) +
- Return a :class:
datecorresponding to date_string, parsed according to - format. This is equivalent to ``date(*(time.strptime(date_string,
- format)[0:3]))``.
I understand that the latest patch includes checking for time fields in date format.
Author: Maciej Szulik (maciej.szulik) *
Date: 2014-04-04 05:45
Alexander yes it's correct. It's checking for time part in date.strptime and for time part in time.strptime. The only problem I came into is that when passing 0 hours or 0 minutes into date.strptime it won't raise an exception, though doc explicitly says: "(...) ValueError is raised if the date string (...) the time part is nonzero". So I'm not sure whether this is enough or should I add additional checks if time part was set?
Author: Alexander Belopolsky (belopolsky) *
Date: 2014-04-04 17:11
If datetime.date.strptime(date_string, format) validates format, then it is not equivalent to date(*(time.strptime(date_string, format)[0:3])), is it?
Author: Maciej Szulik (maciej.szulik) *
Date: 2014-04-04 19:40
You're right, I'll change this description removing 'This is equivalent...' sentence from description. I guess the same applies to time.strptime as well.
Author: Maciej Szulik (maciej.szulik) *
Date: 2014-04-09 20:05
Sorry it took me that long - but I'm finally attaching fixed patch. I've also checked it again current default branch and updated descriptions accordingly.
Author: Mark Lawrence (BreamoreBoy) *
Date: 2015-05-04 18:56
@Alexander as the datetime expert could you get this committed in time for 3.5?
Author: Maciej Szulik (maciej.szulik) *
Date: 2015-05-09 09:51
I've just double checked, this patch applies cleanly to latest tip. I wouldn't mind having this reviewed and merged.
Author: Berker Peksag (berker.peksag) *
Date: 2015-05-09 12:33
datetime.strptime is a classmethod, but the new date.strptime and time.strptime methods are staticmethods. I think we should make the new methods classmethods too.
Author: Maciej Szulik (maciej.szulik) *
Date: 2015-05-11 21:23
Berker per your comment updated patch changing those two new methods (namely date.strptime and time.strptime) to be classmethod and not staticmethods.
Author: Stéphane Wirtel (matrixise) *
Date: 2016-08-08 07:11
Here is an updated version (for 3.6) of the patch of maciej.szulik.
I have executed all the tests.
Please, could you review this patch.
Thank you
Author: Alexander Belopolsky (belopolsky) *
Date: 2016-08-24 14:24
This does not look right:
+.. classmethod:: time.strptime(date_string, format) +
- Return a :class:
timecorresponding to *date_string, parsed according to - format. :exc:
ValueErroris raised if the date string and format can't be - parsed by
time.strptime, if it returns a value which isn't a time tuple, - or if the time part is nonzero. ^^^^^^^^^
Author: Stéphane Wirtel (matrixise) *
Date: 2016-10-24 19:19
belopolsky, could you tell me what it is wrong with the doc about time.strptime ?
Author: Alexander Belopolsky (belopolsky) *
Date: 2016-10-24 19:30
Shouldn't "time part" underlined in my previous note be "date part" instead? Also, does non-zero mean non-empty?
Author: Alexander Belopolsky (belopolsky) *
Date: 2016-10-24 19:31
Never mind the second question.
Author: Matheus Vieira Portela (matheus.v.portela) *
Date: 2017-07-22 08:03
The patch is broken against Python 3.7. I'll try working on it.
Author: Matheus Vieira Portela (matheus.v.portela) *
Date: 2017-07-22 08:04
Also, may I move this issue to a GitHub PR?
Author: Stéphane Wirtel (matrixise) *
Date: 2018-02-07 10:41
I have updated the patch for 3.8, create a PR and fixed the documentation of _strptime._strptime, because this function returns a 3-tuple and not a 2-tuple as indicated in its comment.
Thank you
Author: Stéphane Wirtel (matrixise) *
Date: 2018-03-16 13:34
Hello, just a small reminder for this issue and the PR ;-) when you have time
Author: STINNER Victor (vstinner) *
Date: 2018-07-12 13:37
I removed the easy keyword from this issue: it's open since 2005, it has 12 patches and 1 PR attached, and a lot of discussion.
History
Date
User
Action
Args
2022-04-11 14:56:09
admin
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2018-08-20 19:46:06
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2013-01-22 21:39:42
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title: datetime.strptime constructor added -> Add datetime.time.strptime and datetime.date.strptime
2008-01-06 12:35:14
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2005-01-12 14:53:01
josh-sf
create