[Python-Dev] datetime nanosecond support (original) (raw)

Charles Cazabon charlesc-lists-python-dev2 at pyropus.ca
Wed Jul 25 16:21:25 CEST 2012

Christian Heimes <lists at cheimes.de> wrote:

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.

An alternate strategy might be to use tai64/tai64n/tai64na, which can represent any time over the course of a few hundred billion years to second/nanosecond/attosecond, respectively. They're well-defined, and there's a fair bit of software that can use or manipulate dates in these formats. tai64 is defined similar to propleptic Gregorian in that it uses an idealized 246060 second day, etc.

Charles

Charles Cazabon GPL'ed software available at: http://pyropus.ca/software/

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