[Python-Dev] Subsecond time stamps

Guido van Rossum guido@python.org
Mon, 09 Sep 2002 19:06:30 -0400

> > > C. Make st_mtime a floating point number. This won't offer nanosecond
> > >    resolution, as C doubles are not dense enough.
> >
> > This is the most Pythonic approach.
> -1
> This then locks Python into a specific bit-description notion of a double
> in order to get the appropriate number of significant digits to describe
> time sufficiently.  Embedded/portable processors may not support the
> notion of an IEEE double.
> In addition, timers get increasingly dense as computers get faster.  Thus,
> doubles may work for nanoseconds, but will not be sufficient for
> picoseconds.
> If the goal is a field which never has to be changed to support any amount
> of time, the value should be "infinite precision".  At that point, a
> Python Long used in some tuple representation of fixed-point arithmetic
> springs to mind.  ie. (<long>, <bit of fractional point>)

I'm sorry, but I really don't see the point of wanting to record file
mtimes all the way up to nanosecond precision.  What would it mean?
Most clocks are off by a few seconds at least anyway.

Python has represented time as Pythin floats (implemented as C
doubles) all its life long and it has served us well.

--Guido van Rossum (home page: http://www.python.org/~guido/)