[Python-Dev] PEP 495 Was: PEP 498: Literal String Interpolation is ready for pronouncement (original) (raw)

Alexander Belopolsky alexander.belopolsky at gmail.com
Sat Sep 12 03:23:45 CEST 2015

On Fri, Sep 11, 2015 at 8:56 PM, Random832 <random832 at fastmail.com> wrote:

Alexander Belopolsky <alexander.belopolsky at gmail.com> writes: > There is no "earlier" or "later". There are "lesser" and "greater" > which are already defined for all pairs of aware datetimes. PEP 495 > doubles the set of possible datetimes

That depends on what you mean by "possible".

What exactly depends on the meaning of "possible"? In this context "possible" means "can appear in a Python program."

> and they don't fit in one > straight line anymore. The whole point of PEP 495 is to introduce a > "fold" in the timeline.

That doesn't make sense. Within a given timezone, any given moment of UTC time (which is a straight line [shut up, no leap seconds here]) maps to only one local time. The point of PEP 495 seems to be to eliminate the cases where two UTC moments map to the same aware local time.

Yes, but it does that at the cost of introducing the second local "01:30" which is "later" than the first "01:40" while "obviously" (and according to the current datetime rules) "01:30" < "01:40".

Out of curiosity, can "fold" ever be any value other than 0 or 1?

Thankfully, no.

> Yes, but are we willing to accept that datetimes have only partial > order? I apparently haven't been following the discussion closely enough to understand how this can possibly be the case outside cases I assumed it already was (naive vs aware comparisons being invalid).

Local times that fall in the spring-forward gap cannot be ordered interzone even without PEP 495. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://mail.python.org/pipermail/python-dev/attachments/20150911/6091e83f/attachment.html>

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