[Python-ideas] datetime: Support infinity

[Yawar Amin]

Hi Chris, sorry for the top-posting; replying from my phone.

My test implementation works for me on Python 2.7, see http://repl.it/9Wz

Notice especially the last few assertions, where normal datetime objects are on the LHS.

Regards,

Yawar

On 2015-01-29, at 2:04, Chris Barker <chris.barker at noaa.gov> wrote:

> On Wed, Jan 28, 2015 at 6:55 PM, Yawar Amin <yawar.amin at gmail.com> wrote:
>> Cool, the comparison operator logic looks very similar to mine:
>> 
>> https://groups.google.com/d/msg/python-ideas/G3jeWoa6h14/ELpDLFu28QcJ
> 
> Did you get it to work both ways? i.e.
> 
> datetime.neg_inf < datetime.now()
> 
> and 
> 
> datetime.now() > datetime.neg_inf 
> 
> I had trouble with that, because the regular datetime doesn't know how to compare itself to a neg_inf object.
>  
>> I believe the ideal design is the following type hierarchy:
>> 
>>     datetime_base
>>       datetime_neg_inf
>>       datetime_pos_inf
>>       datetime
>> 
>> But in the interests of pragmatism, I think this one can be made to
>> work:
>> 
>>     datetime
>>       datetime_neg_inf
>>       datetime_pos_inf
> 
> yup -- should work.
> 
> and you could add class methods to the datetime object, so you could do:
> 
> datetime.neg_inf()
> and
> datetime.pos_inf()
>  
>> The
>> advantage to this is that we don't have to switch everything over to
>> using a new derived type--just use the normal datetime for the majority
>> of cases where we don't need inifinity dates.
> 
> And it could be a third part package, too. -- particularly good for backward compatibility.
> 
> -Chris
> 
> 
> -- 
> 
> Christopher Barker, Ph.D.
> Oceanographer
> 
> Emergency Response Division
> NOAA/NOS/OR&R            (206) 526-6959   voice
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> 
> Chris.Barker at noaa.gov
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