[Python-Dev] Subsecond time stamps
Guido van Rossum
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.
> 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
> 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/)