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[Python-Dev] datetime nanosecond support

Christian Heimes lists at cheimes.de
Wed Jul 25 15:59:03 CEST 2012 
Am 25.07.2012 13:48, schrieb Antoine Pitrou:
>> I'd vote for two separate numbers, the first similar to JDN (Julian Day
>> Number [1]), the second for nanoseconds per day. 3600 * 1000000 fit
>> nicely into an unsigned 32bit int.
> 
> But 24 * 3600 * 1e9 doesn't. Perhaps I didn't understand your proposal.

What the h... was I thinking? I confused nano with micro and forgot the
hours, how embarrassing. :(

days
----
32bit signed integer

numbers of days since Jan 1, 1 AD in proleptic Gregorian calendar (aka
modern civil calendar). That's Rata Die minus one day since it defines
Jan 1, 1 AD as day 1. This allows days between year 5.8 Mio in the past
and 5.8 Mio in the future ((1<<31) // 365.242 ~ 5879618).

nanoseconds
-----------
64bit signed or unsigned integer

more than enough for nanosecond granularity (47bits), we could easily
push it to pico seconds resolution (57bits) in the future.


Christian
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