[Python-ideas] Please reconsider the Boolean evaluation of midnight

[Donald Stufft]

On Mar 5, 2014, at 5:35 PM, M.-A. Lemburg <mal at egenix.com> wrote:

> On 05.03.2014 23:16, Ben Finney wrote:
>> "M.-A. Lemburg" <mal at egenix.com> writes:
>> 
>>> I don't know what all the fuzz is about. There are lots of types
>>> in Python that evaluate to False in certain corner cases, e.g.
>>> "", (), [], {}, 0, 0.0, 0j, None, etc.
>>> 
>>> datetime.time(0,0,0) is just another one :-)
>> 
>> The salient difference is:
>> 
>> With the former set, they all embody concepts of either “empty” or “zero
>> magnitude”. They strongly connote “not there” within their domain of
>> values, hence map well to Boolean false.
>> 
>> With ‘datetime.time’ there is no equivalent: midnight is not special in
>> the way “empty” or “zero magnitude” are. Midnight is an arbitrary point
>> on a continuum, and is not a “not there” value.
> 
> This is true in a date/time continuum, but not true if you regard
> time as "time of day". In the latter interpretation, the day starts
> at midnight, so the day is "not there" yet at midnight.

The day is absolutely here at midnight. Midnight isn’t some void where
time ceases to exist.

> 
>> It should not be Boolean false any more than any other time.
> 
> Just like with most interpretations, you can just as easily find
> one which implies the exact opposite.
> 
> It's all smoke and mirrors anyway :-)
> 
> Perhaps Tim just wanted to be able to make float(time(0,0,0)) return
> 0.0 seconds some day. That's what mxDateTime does for time values.
> 
> -- 
> Marc-Andre Lemburg
> eGenix.com
> 
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-----------------
Donald Stufft
PGP: 0x6E3CBCE93372DCFA // 7C6B 7C5D 5E2B 6356 A926 F04F 6E3C BCE9 3372 DCFA

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