[ANN] Chalten - A Point Based Model of the Gregorian Calendar

Hi,
we uploaded to SourceForge and the Cincom Public Repository a new
project called "Chalten" that is the implementation of the Gregorian
Calendar model we presented last year at ESUG.
This model reifyes many concepts of the Gregorian Calendar that
Smalltalk-80 does not (like day, day of month or a month of year, etc).
This model was born one year and a half ago but we just be able to open it.
The main objective of this model is to easily solve problems of the
Gregorian Calendar that are not so easy to do with the Smalltalk-80
classes. It provides also some concepts that are useful for financial
applications like TimeLineFilter and RelativeGregorianDate.
This model also uses the units models (Aconcagua) we uploaded last week.
Because it uses the units model, there are some concepts that are not
useful anymore, like Duration, because a Duration is a Measure of time.
Anyway, you can read about the model in the FAQ (a document we uploaded
to SourceForge and SqueakSource), the ESUG presentation from
http://prog2.vub.ac.be/~cderoove/esugtalks/Wilkinson.pdf and the paper
from
http://www.iam.unibe.ch/publikationen/techreports/2005/iam-05-001/file/at_download 


It comes with almost 600 tests and you can read in the paper how it
compares to Chronology (the Squeak package) and the ANSI Smalltalk
extensions.
The FAQ talks a little bit about how it compares to Chronos.
Here are some examples I hope you will like:

January first, 2006 --> Creates an instance of GregorianDate for 01/01/2006
January first --> Creates an instance of GregorianDayOfMonth for 01/01
January, 2006 --> Creates an instance of GregorianMonthOfYear for
January 2006

January first, 2006 distanceTo: July first, 2006 --> Returns an instance
of Measure "181 days"

(GregorianYear number: 2006) months collect: [ :aMonthOfYear |
aMonthOfYear lastDate ] -->Returns all the last dates of the 2006 months.
(GregorianYear number: 2006) dates collect: [ :aDate | aDate isMonday ]
-->Returns all Mondays of 2006

“Let’s create a filter for all dates...”
nonWorkingDays := TimelineFilter universe: (TheBeginningOfTime to:
TheEndOfTime).
“Now, we want Saturdays to be on that filter”
nonWorkingDays addDayRule: Saturday.
“Now we want Sundays from January 1st of year 1000 to the end of time...”
nonWorkingDays addDayRule: Sunday from: (January first, 1000) to:
TheEndOfTime.
“Now we want all July 9th since 1816 because is the Independence Day in
Argentina”.
nonWorkingDays addDayOfMonthRule: July ninth from: (July ninth, 1816)
to: TheEndOfTime.
nonWorkingDays includes: (July ninth, 2005) “Returns true”
nonWorkingDays includes: (July eighth, 2005) “Returns false”
nonWorkingDays includes: (July sixteenth, 2005) “Returns true, it is
Saturday”
“06/01/2005 is a Thursday”
aTimespan := GregorianTimespan from: (January sixth, 2005) duration: 48
hours.
aSettleDate := RelativeGregorianDate timespan: aTimespan calendar:
nonWorkingDays negated.
“Returns false because 10/01/2005, a Monday, is a working day”
nonWorkingDays includes: (January tenth, 2005).
“Returns 10/01/2005”
aSettleDate absoluteDate.
”Now a new non working day is added to the filter”
nonWorkingDays addDateRuleFor: (January tenth, 2005).
“Return true. Now 10/01/2005, is a not working day”
nonWorkingDays includes: (January tenth, 2005).
“Now it returns 11/01/2005 because the filter has changed”
aSettleDate absoluteDate.

Hernan.

--
______________________________
Lic. Hernán A. Wilkinson
Gerente de Desarrollo y Tecnología
Mercap S.R.L.
Tacuari 202 - 7mo Piso - Tel: 54-11-4878-1118
Buenos Aires - Argentina
http://www.mercapsoftware.com
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