It is heavily inspired by [Carbon](http://carbon.nesbot.com) for PHP.
Basically, the Pendulum class is a replacement for the native datetime one with some useful and intuitive methods, the Interval class is intended to be a better time delta class and, finally, the Period class is a datetime-aware timedelta.
Timezones are also easier to deal with: Pendulum will automatically normalize your datetime to handle DST transitions for you.
import pendulum
pendulum.create(2013, 3, 31, 2, 30, 0, 0, 'Europe/Paris’)
# 2:30 for the 31th of March 2013 does not exist
# so pendulum will return the actual time which is 3:30+02:00
'2013-03-31T03:30:00+02:00’
dt = pendulum.create(2013, 3, 31, 1, 59, 59, 999999, 'Europe/Paris’)
'2013-03-31T01:59:59.999999+01:00’
dt = dt.add(microseconds=1)
'2013-03-31T03:00:00+02:00’
dt.subtract(microseconds=1)
'2013-03-31T01:59:59.999998+01:00’
Link to the official documentation: https://pendulum.eustace.io/docs/
Link to the github project: https://github.com/sdispater/pendulum
What if you were to begin with a time at 3:30 and then subtract an hour. Would your library properly return 1:30? What if a user had a naive time at 3:30, subtracted an hour, and then converted to an aware time using your library? For what it's worth, I think moving to 3:30 is the correct behaviour in the vast amount of cases. Requiring a user to provide a direction to move and throwing an exception if they don't is dangerous. How often are users going to see this exception, if at all? Just wondering how much you've considered cases, if they exist, that would be better off moving to 1:30.
I'll add one more thing. As soon as I started browsing the page I thought "why would I use this over arrow?". Great to see you addressed that by default. I didn't know about some of arrows shortcomings/bugs, so they were really useful.
Handling dates, times, and timezones in particular is a tricky problem, as evident by the large number of libraries in each language trying to get it right. If you haven't already, I'd really recommend reading the blog posts of Jon Skeet regarding Noda Time http://blog.nodatime.org/ and https://codeblog.jonskeet.uk/category/nodatime/ even if it turns up some corner cases you haven't considered, or validates ones you have.
Thanks!
https://www.python.org/dev/peps/pep-0495/
It adds an extra attribute 'fold' that can be '0' (the default) for normal times and '1' for the later version with that same local time representation in the case of the clock going backwards.
What is important here, I think, is that any time arithmetic is not affected by this normalization, so if you add an hour the difference will be an hour, so you don't really have to think about it.
At least that was my impression from trying to find a combination of libraries I like and reading various bug trackers in the process. In the end I pick and choose the pieces that do what I like for each part of the process, luckily the datatypes are mostly compatible or easily adapted.
On the otherhand if you've e.g. Ruby/Rails datetime handling than you get used to reasonable things working ( such as Time.now + 1.day ) that Arrow doesn't handle well. As a matter of fact Arrow got rid of DT deltas and seemingly made the situation worse.
I've only looked at the examples in the docs; but to be serious, Python should just scrap their DT/time/calendar libs and copy Ruby verbatim. This NIH thing needs to stop..
Related: http://stackoverflow.com/questions/441147/how-can-i-subtract...
I don't see anything unreasonable about Pendulum's interface. Let's let Python be Python and Ruby be Ruby.
Sorry for the rant, but I've spent many years as the only California developer for a time based in the UK, suffering the tyranny of developers who spend half their year blissfully living in UTC and unknowingly foisting off their dirty time zone bugs on me.
[0]: http://ruby-doc.org/core-1.9.3/Integer.html#method-i-times
now_in_paris = pm.now('Europe/Paris')
tomorrow_in_paris = now_in_paris + pm.day
next_week_in_paris = now_in_paris + 7*pm.day
>>> from datetime import datetime, timedelta
>>> datetime.now() - (datetime.now() + timedelta(days=1))
datetime.timedelta(-2, 86399, 999969)Try:
>>> from datetime import datetime, timedelta
>>> now = datetime.now()
>>> now - (now + timedelta(days=1))
datetime.timedelta(-1)Also I really hate when someone fragment the energy and their time making a new, inferior library instead of fixing and patching the existings for basic things like this. This way we will have a bunch of incomplete, inferior libraries which all have quirks instead of only one really good one which could everybody use...
Second, I think it's great that people are making alternatives - it promotes a healthier ecosystem where people can share good ideas as well.
> instead of fixing and patching the existings Finally, by your logic, the popular requests library shouldn't have existed and Kenneth would have been patching the more conventional urllib library
This library did not born because of fun, but because of solving a (non-existing) problem from frustration. I would have not said one word if he was doing this for fun or just learning or something like that.
The README for Pendulum seems to show me one feature Delorean doesn't explicitly have -- `is_weekend()` -- otherwise these libraries are conceptually very similar.
I do agree that this (and Delorean) is a usability improvement over `datetime` and perhaps even Arrow (though I'm not tremendously familiar with Arrow).
Also, Pendulum is not just about datetimes but also provides both the Interval class and Period class which are improvements over the native timedelta class.
And finally, it handles properly time shifting around DST transition times and normalization of datetimes when creating them which neither Delorean nor Arrow do well.
There have been steady discussions of this issue for almost four years now. I dropped out years ago, but the arguments go on.
Where exactly in email to do they appear? In the header, it's been my experience they all conform to the RFC 2822 spec, and could be parsed with the standard library function email.utils.parsedate_tz[1].
[1] https://docs.python.org/2/library/email.util.html#email.util...
[1] http://infiniteundo.com/post/25326999628/falsehoods-programm... [2] http://infiniteundo.com/post/25509354022/more-falsehoods-pro...
In [34]: pd.Timestamp('2016-08') == pd.Timestamp('2016.08') == pd.Timestamp('2016/08') == pd.Timestamp('08/2016')
Out[34]: True
In [38]: pd.Timestamp('2016') == pd.Timestamp(datetime.datetime(2016,1,1))
Out[38]: True
In [49]: pd.Timestamp('2016') + pd.offsets.MonthOffset(months=7) == pd.Timestamp('2016-08')
Out[49]: True
In [52]: pd.Timestamp.now()
Out[52]: Timestamp('2016-08-17 08:01:07.576323')
In [53]: pd.Timestamp.now() + pd.offsets.MonthBegin(normalize=True)
Out[53]: Timestamp('2016-09-01 00:00:00')
Not saying storing user timezone and converting on the backend is bad; but this is simpler when localized timestamps aren't a core part of my app.
If a Samoan user told you to record an event for January 1st 2012 on January 1st 2011, if you stored the date in UTC would have reminded them on January 2nd 2012 (all local).
Because in May 2011 Samoa announced they were going to skip a local day and move across the international date line. So 2011-12-30T09:00:00 UTC was 2011-12-29T23:00:00 Pacific/Apia, but 2011-12-30T10:00:00 UTC was 2011-12-31T00:00:00 Pacific/Apia.
In some cases it guesses what you meant:
>>> pendulum.create(2013, 3, 31, 2, 30, 0, 0, 'Europe/Paris')
'2013-03-31T03:30:00+02:00' # 2:30 does not exist (Skipped time)
pendulum.parse('2016-06-31')
# ValueError: day is out of range for monthAnybody know of an elegant solution/library or even a library that would be open to including such a concept?
Eg, spot the error:
_weekend_days = [SATURDAY, SUNDAY]
date.is_weekend = date.day in _weekend_days
(TIL one country doesn't even have consecutive weekend days)
pendulum.set_weekend_days([pendulum.SUNDAY])I think the `in_words()` function should probably be delimited by commas though, good to have your strings easily deconstructed into their constituent parts.