I rejected datetime.datetime because I want to get nanosecond resolution for time and os modules, not only for the os module. If we choose to only patch the os module (*stat() and *utime*() functions), datetime.datetime would be meaningful (e.g. it's easier to format datetime for an human, than a Epoch timestamp). I don't think that it's a real issue that datetime is not fully compatible with float. If os.stat() continues to return float by default, programs asking explicitly for datetime would be prepared to handle this type. I have the same rationale with Decimal :-) I don't think that there is a need to support datetime+int or datetime-float, there is already the timedelta type which is well defined. For os.stat(), you should use the UTC timezone, not a naive datetime.
* Add a new parameter to functions that produce stat-like timestamps to explicitly specify the type of the timestamps (float or datetime), as proposed in PEP 410.
What is a stat-like timestamp? Which functions are concerned?
Similarly, I realize os.stat_float_times was always a bit of a hack, what with it being global state and all. However the approach has the virtue of having worked in the past.
A global switch to get timestamps as datetime or Decimal would break libraries and programs unable to handle these types. I prefer adding an argument to os.*stat() functions to avoid border effects. Read also: http://www.python.org/dev/peps/pep-0410/#add-a-global-flag-to-change-the-tim...
Specficially addressing PEP 410's concerns:
* I don't propose doing anything about the other functions that have no explicit start time; I'm only proposing changing the functions that deal with timestamps. (Perhaps the right thing for epoch-less times like time.clock would be timedelta? But I think we can table this discussion for now.)
We may choose a different solution for the os.stat()/os.utime() and for the others functions (see the PEP 410 for the full list). But I would prefer an unified solution to provide nanosecond resolution in all modules. It would avoid to have to support two new types for example. Victor