On Jan 5, 2010, at 1:43 PM, mmalc Crawford wrote:
>
> On Jan 5, 2010, at 1:35 pm, Kyle Sluder wrote:
>
>> On Tue, Jan 5, 2010 at 1:23 PM, mmalc Crawford <mmalc_li...@me.com> wrote:
>>> An NSDate object represent a single point in time -- you can think of it
>>> basically as a wrapper for an NSTimeInterval from the reference date. If
>>> you want to create components from the date, then you must do so with
>>> respect to a particular calendar *and time zone*... This is of course
>>> possible, but then you have to be careful about always using the same
>>> combination of calendar and time zone to create the components and recreate
>>> the date from the components.
>>
>> I believe that Quincey's argument is that it is conceptually
>> inaccurate in most cases to think of a point in time as simply an
>> interval from a reference date. I agree that in contexts where words
>> like "today" are meaningful, he's probably right. Especially in
>> calendaring/scheduling apps. Given the number of people who struggle
>> with the concept of daylight saving time, I am not surprised that I
>> have yet to meet a non-technical person who could conceptualize a
>> "point in time" independently of a calendar system.
>>
> I'm not sure what the point is here, though?
> It's the job of the application to present to the user a representation of a
> date that they can understand. It's the job of the programmer to interpret
> that unambiguously such that it can be stored and recreated -- which is the
> issue here. Talking about date components in the abstract as if any date can
> arbitrarily be reduced to a collection of components without reference to any
> other context (the calendar and time zone) is misleading.
For more fun with calendars, Wall(et) Street Journal had a nice article
yesterday:
http://online.wsj.com/article/SB126212850216209527.html
Cheers,
. . . . . . . . Henry
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