[Python-Dev] datetime nanosecond support (ctd?)

[Guido van Rossum]

"Nothing looks quite right" is a common phenomenon when you're constrained
by backward compatibility. The perfect solution would throw away
compatibility, but that has its own downsides. So just go for what looks
the least wrong.

On Tue, Dec 16, 2014 at 3:28 PM, Matthieu Bec <mbec at gmto.org> wrote:
>
>
> Maybe what I meant with `nothing looks quite right':
> seconds as float, microseconds as float, nanosecond as 0..999, nanoseconds
> as 0..999999999 with mandatory keyword that precludes microseconds - all
> can be made to work, none seems completely satisfying.
>
> In fact, I don't really have a use for it from python - but something
> would be needed in C for the implementation of datetime.from_timespec and
> time.from_timespec that calls the constructor PyObjectCall_CallFunction(clas,"...",...)
> - can this happen and remain hidden from the python layer?
>
> Regards,
> Matthieu
>
>
>
> On 12/16/14 12:45 PM, Alexander Belopolsky wrote:
>
>>
>> On Tue, Dec 16, 2014 at 12:10 PM, matthieu bec <mbec at gmto.org
>> <mailto:mbec at gmto.org>> wrote:
>>
>>     I wonder if the datetime module is really the right location, that
>>     has constructor(year, month, day, ..., second, microsecond) - with
>>     0<ms<999999, no millis. adding 0<ns<999 would seem quite ugly, in
>>     fact nothing looks quite right.
>>
>>
>> We can make nanosecond a keyword-only argument, so that
>>
>> time(1, 2, 3, nanosecond=123456789) -> 01:02:03.123456789
>>
>> and
>>
>> time(1, 2, 3, 4, nanosecond=123456789) -> error
>>
>> Users will probably be encouraged to avoid positional form when
>> specifying time to subsecond precision.  I would say  time(1, 2, 3,
>> microsecond=4) is clearer than time(1, 2, 3, 4) anyways.
>>
>> Another option is to allow float for the "second" argument:
>>
>> time(1, 2, 3.123456789) -> 01:02:03.123456789
>>
>>
>>
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>>
> --
> Matthieu Bec                GMTO Corp
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-- 
--Guido van Rossum (python.org/~guido)
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