[Glass] Kind of _asDaysFrom1970 that answers negative numbers?

[Mariano Martinez Peck via Glass]

On Thu, Feb 23, 2017 at 6:37 PM, Richard Sargent <
richard.sargent at gemtalksystems.com> wrote:

> #julianDay is also a primitive. Couple it with a pre-computed Julian day
> for January 1, 1970. The subtraction is also fast.
>
> (Date newDay: 1 year: 1960) julianDay - (Date newDay: 1 year: 1970)
> julianDay
>
> -3653
>
>
> Unless this date conversion is THE bottleneck in your system, you are
> wasting time on unnecessary optimizations. Remember the rule "measure
> first, then optimize" (coupled with "micro-optimizations are usually as
> useful as micro-benchmarks").
>


Hi Richard,

Yes, I got up to this far on this method as a result of ProfMonitor. I was
using the same code for calculating this I was using on Pharo and that was
very slow. Then I found the  _asDaysFrom1970 and that was fast.

I just tried your idea, and indeed it looks as fast as the one with the
primitive. That tells me the speedup was not because of the primitive but
that in fact I was doing something very slow on my old implementation (the
one I had for Pharo). Thank you very much!


Why this is a bottleneck for me? Well... the long short story is that I
have some financial reports where the user may have N number of charts.
Say... 8 charts average. Each chart may have M numbers of series. Say... 5.
These series could be "price-related" series from which we have companies
that go back up to 1930. Not only prices but also some other financial data
(indexes etc) that also go way beyond 1970. All these series are then
answered via JSON to the chart library. And there is where I convert the
dates to miliseconds since epoch. Of course, we have things to provide
"less resolution" for chats instead of the super daily/hourly resolution
etc etc. But that's an story for a different day.

Thanks Richard,




>
>
>
> On Thu, Feb 23, 2017 at 3:30 PM, Mariano Martinez Peck via Glass <
> glass at lists.gemtalksystems.com> wrote:
>
>> Hi guys,
>>
>> I am using  _asDaysFrom1970 to convert Smalltalk dates to Javascript
>> dates that I pass via JSON (as milliseconds since 1907 epoch) to a chart
>> library.
>>
>> The problem is that I need this even for dates before 1970. I checked
>> that:
>>
>> 1) JS can accept this:
>>
>> new Date(-100000000)
>> ->  Tue Dec 30 1969 17:13:20 GMT-0300 (ART)
>>
>> 2) The chart lib  I use, I can also specify this:
>>
>>    data: [
>>             [-1394104654000, 42],
>>         ]
>>
>>
>> So... my remaining problem is that I would like a primitive-based (for
>> performance) like _asDaysFrom1970 but that knows how to answer negative
>> numbers for those dates prior to 1970.
>>
>> Do we have already something like this? Could this be added?
>>
>> Below is the method in question.
>>
>> Thanks in advance,
>>
>> Best regards.
>>
>>
>> ---------------------
>>
>>
>> _asDaysFrom1970
>>   "Convert the receiver to a SmallInteger representing the number of days
>> since
>> January 1, 1970."
>>
>>   "Primitive does not support instances which represent a date before
>> 1970."
>>
>>   <primitive: 540>
>>   ^ self _primitiveFailed: #'_asDaysFrom1970'
>>
>>
>>
>>
>> --
>> Mariano
>> http://marianopeck.wordpress.com
>>
>> _______________________________________________
>> Glass mailing list
>> Glass at lists.gemtalksystems.com
>> http://lists.gemtalksystems.com/mailman/listinfo/glass
>>
>>
>


-- 
Mariano
http://marianopeck.wordpress.com
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