[Python-Dev] Proposing an alternative to PEP 410

[Simon Cross]

On Sun, Feb 26, 2012 at 1:31 AM, Guido van Rossum <guido at python.org> wrote:
> I still think that when you are actually interested in *using* times,
> the current float format is absolutely fine. Anybody who thinks they
> need to accurately know the absolute time that something happened with
> nanosecond accuracy is out of their mind; given relativity such times
> have an incredibly local significance anyway.

There are good scientific use cases for nanosecond time resolution
(e.g. radio astronomy) where one is actually measuring time down to
that level and taking into account propagation delays. I have first
hand experience of at least one radio telescope (MeerKAT) that is
using Python to process these sorts of timestamps (Maciej even gave a
talk on MeerKAT at PyCon 2011 :).

Often these sorts of applications just use an large integer to hold
the time. Higher-level constructs like datetime tend to be too bulky
and provide functionality that is not particularly relevant. There is
also a lot of pressure to have all the details coded by an in-house
expert (because you need complete control and understanding of them,
so you might as well do it yourself rather than continually patch,
say, Python, to match your instrument's view of how this should all
work).

Hardware capable of generating nanosecond accurate timestamps is,
however, becoming fairly easy to get hold of (a suitable crystalline
clock slaved to a decent GPS unit can get you a lot of the way) and
there are probably quite a few applications where it might become
relevant.

I'm not sure whether any of this is intended to be for or against any
side in the current discussion. :D

Schiavo
Simon