[Python-Dev] Status on PEP-431 Timezones (original) (raw)

Lennart Regebro regebro at gmail.com
Wed Apr 8 23:47:45 CEST 2015

On Wed, Apr 8, 2015 at 9:57 PM, Isaac Schwabacher <ischwabacher at wisc.edu> wrote:

On 15-04-08, Lennart Regebro wrote:

=== Stdlib option 2: A datetime isdst flag ===

By having a flag on the datetime instance that says "this is in DST or not" the timezone implementation can be kept simpler. Storing the offset itself instead of a flag makes things conceptually cleaner.

The concept would be pretty much the same, but yes, you would be able to save lookups in the dst() call, so that's a benefit. I was planning on storing the dst() offset at least lazily, but I'm not sure that means we can get rid of the flag.

As an added bonus, you get a representation that's still meaningful when time changes happen for political rather than DST reasons.

That's a good point. Although you would still have to use the is_dst flag to choose in that case, even if neither or both is actually DST. Unless we come up with another name for that flag, which I don't think is important.

//Lennart

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