[Python-Dev] Status on PEP-431 Timezones

[Lennart Regebro]

OK, so I just had a realization.

Because we want some internal flag to tell if the datetime is in DST
or not, the datetime pickle format will change. And the datetime
pickle format changing is the biggest reason I had against changing
the internal representation to UTC.

So because of this, perhaps we actually *should* change the internal
representation to UTC, because that makes the issues I'm fighting with
now so much simpler. (I'm currently trying to get arithmetic to do the
right thing in all cases, which is crazy complicated).

We can add support to unpickle previous datetimes, but we won't be
able to add forwards compatibility, meaning that pickles saved in
Python 3.5 will not be unpicklable in Python 3.4.

Please discuss.

//Lennart