The Timing of Time

Francisco Garau francisco.garau at gmail.com
Fri Apr 14 10:31:12 UTC 2006


Hi Alan,

As yourself, I am also interested in date and times. I tried loading the 
Chronos package following the instructions from your website [1], but 
something went awry.

I succesfully loaded:
    1- Passport-Kernel
    2- Passport-Squeak
    3- Chronos-System-Squeak
    4- Chronos-System-Squeak-PostV3.6

The problem happens on step 3. The last two lines of that fileOut says:

    ChronosSqueakEnvironment initialize !
    ChronosEnvironment canonical install !

I guess that ChronosEnvironment should be a class and canonical a message. 
But neither of them are in the image.

My interest on dates is more biased towards dates than towards times. Dates, 
months, years and calendars are central objects in financial systems. 
Amongst the many problems that arises in such systems, here a couple of 
examples:

- Starting on the 31Mar2006 generate a schedule of payments every month 
until 31Mar2007.
That should return 30Apr06 31May06 30Jun06 ... 28Feb07 31Mar07

- Adjust the previous schedule to the british and japanese calendar, making 
sure all dates are 'good business days'. So, for example, if 30Apr06 falls 
on Sunday or a british bank holiday, change it according to some rule. 
Examples of such rules are:
next business day, next calendar day, etc.

It gets more complicated when you think about DCC (day count conventions). 
In the first example we were dealing with actual months. But under the 
30/360 DCC, every month has 30 days.

Dates can be seen from many different points of view. In a financial system 
we are certainly not interested in the duration of a date. Not in 
nanoseconds, not in milliseconds or even hours. A date is a business date.

I agree with the Mercap guys that dates, months and years are views of the 
same time-line at different levels of granularity. In financial systems we 
don't need to go further down that date. For other type of systems requiring 
global syncronization, you probably need to go down to the millisecond 
level. Furthermore, you need every time to be expressed as an offset from a 
central location (Greenwich?).

That is my poor understanding of time-zones and the reason why I want to 
play with the Chronos package.

Cheers,
Francisco

[1] http://chronos-st.org/frames/Squeak-Downloads.html
[2] http://article.gmane.org/gmane.comp.lang.smalltalk.squeak.general/100148




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