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

[M.-A. Lemburg]

On 05.03.2014 23:38, Donald Stufft wrote:
> 
> 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.

No, but midnight starts the day, just like 0 starts the positive
real numbers (itself not being positive) :-)

>>> 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
>>
>> Professional Python Services directly from the Source  (#1, Mar 05 2014)
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>> ________________________________________________________________________
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> 
> 
> -----------------
> Donald Stufft
> PGP: 0x6E3CBCE93372DCFA // 7C6B 7C5D 5E2B 6356 A926 F04F 6E3C BCE9 3372 DCFA
> 

-- 
Marc-Andre Lemburg
eGenix.com

Professional Python Services directly from the Source  (#1, Mar 05 2014)
>>> Python Projects, Consulting and Support ...   http://www.egenix.com/
>>> mxODBC.Zope/Plone.Database.Adapter ...       http://zope.egenix.com/
>>> mxODBC, mxDateTime, mxTextTools ...        http://python.egenix.com/
________________________________________________________________________
2014-04-09: PyCon 2014, Montreal, Canada ...               35 days to go

::::: Try our mxODBC.Connect Python Database Interface for free ! ::::::

   eGenix.com Software, Skills and Services GmbH  Pastor-Loeh-Str.48
    D-40764 Langenfeld, Germany. CEO Dipl.-Math. Marc-Andre Lemburg
           Registered at Amtsgericht Duesseldorf: HRB 46611
               http://www.egenix.com/company/contact/