[Python-Dev] Proposing an alternative to PEP 410

[Larry Hastings]

On 02/23/2012 02:35 PM, Victor Stinner wrote:
> 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 think a piecemeal approach would be better.  I'm aware of a specific 
problem with os.stat / os.utime--the loss of precision problem that's 
already been endlessly discussed.  Is there a similar problem with these 
other functions?


> 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.

I suggest this because I myself have written (admittedly sloppy) code 
that assumed it could perform simple addition with st_mtime.  Instead of 
finding out the current timestamp and writing that out properly, I 
occasionally read in the file's mtime, add a small integer (or even 
smaller float), and write it back out.


> For os.stat(), you should use the UTC timezone, not a naive datetime.

Why is that more appropriate?  IIUC, timestamps ignore leap seconds and 
strictly represent "seconds since the epoch".  In order to correctly 
return a time in the UTC time zone we'd have to adjust for leap 
seconds.  Naive datetimes bask in their happy ignorance of such 
complexities.


//arry/
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