[Datetime-SIG] Another round on error-checking
tim.peters at gmail.com
Tue Sep 1 19:44:47 CEST 2015
> Here is an idea that I think may work: let's consider fold=1 instances as if
> they have a different tzinfo instance from the other side in both datetime
> subtractions and comparisons. This will be consistent with the current
> stdlib and pytz work-arounds of representing "second" times using fictitious
> fixed-offset timezones.
That's what I was getting at by saying "fold=1 veritably _screams_
'I'm no longer working in naive time'". Which implies "I need
timeline arithmetic", and everything else follows from that, including
hash() not ignoring fold=1 either.
But then the concept of "naive time" gets muddier: sometimes, e.g.,
dt1 - dt2
in a common zone (same tzinfo) will use classic arithmetic, but in
other cases (fold=1 in at least one) timeline arithmetic.
And there's also that, after
d = dt1 - dt2
I suspect it may no longer always be the case that
dt1 == dt2 + d
(unsure, but can't make time for it now)
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