On 19 May 2012 01:55, Eliot Miranda <eliot.miranda at gmail.com> wrote:
>
>
> On Fri, May 18, 2012 at 4:47 PM, David T. Lewis <lewis at mail.msen.com> wrote:
>>
>> On Fri, May 18, 2012 at 09:30:32PM +0200, Bert Freudenberg wrote:
>> > On 18.05.2012, at 19:22, Eliot Miranda wrote:
>> >
>> > > 'From Smalltalk-80, version 2, of April 1, 1983 on 31 May 1983 at
>> > > 9:10:35 am'!
>> >
>> > That's obviously an April Fool's joke ;)
>> >
>> >
>> > But very interesting indeed. I had assumed that the way Squeak handles
>> > time is identical to how Smalltalk-80 did it. Apparently not, they must
>> > have simplified in the Mac version.
>> >
>> > - Bert -
>> >
>>
>> The original Squeak implementation of Time class>>totalSeconds uses
>> primSecondsClock, which is documented as:
>>
>> primSecondsClock
>>        "Answer the number of seconds since 00:00 on the morning of
>>         January 1, 1901 (a 32-bit unsigned number).
>>         Essential. See Object documentation whatIsAPrimitive. "
>>
>> This does not specify whether it refers to the local time zone or to GMT,
>> and the actual implementation in Squeak has always used local time.
>>
>> The Blue Book documents Time class>totalSeconds as "Answer the total
>> seconds
>> from Jan. 1, 1901, corrected for time zone and daylight savings time."
>>
>> And Time class>>timeWords is "Answer the seconds (in Greenwich Mean Time)
>> since Jan. 1, 1901 ..."
>>
>> So it certainly does sound like totalSeconds was intended to be seconds
>> since Jan. 1, 1901 GMT, and it also appears that totalSeconds has been
>> implemented differently in Squeak.
>>
>> After seeing Eliot's code reference, I'm inclined to think that the Blue
>> Book provided an unambiguous definition (though poorly worded), and that
>> Squeak has apparently been implementing it differently all along. There
>> is nothing in the Squeak image itself that gives a clue as to the original
>> intent (Time class>>timeWords is not present in Squeak), so the
>> conflicting
>> implementations are now in wide circulation.
>>
>> None of this does much to convince me that refering to a clearly defined
>> Posix epoch would be a bad idea ...
>
>
> Bit it's so dull ;)  The start of the 20th century, albeit the traditional
> 01 start instead of the colloquial 00 start, is so much nicer.  I strongly
> suspect that 1970 was chosen more because of the absence of large integer
> arithmetic in libc (31 bit seconds run aground in 2038), and so is mere
> pragmatism.  Some of us were already born in 1970, and I hate being
> negative.
>
i'm in a mood of extending your metaphor :)
Now i can clearly tell, what caused the extinction of dinosaurs! :)

>>
>> Dave
>>
>>
>
>
>
> --
> best,
> Eliot
>
>
>
>



-- 
Best regards,
Igor Stasenko.