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

Random832 random832 at fastmail.com
Sat Sep 12 02:56:27 CEST 2015

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".

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.

Out of curiosity, can "fold" ever be any value other than 0 or 1? I don't know if there are any real-world examples (doubt it), but I could easily contrive a timezone definition that had three of a particular clock time.

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).

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