From: Edvard Majakari <edvard@...>
Date: 2008-09-04T05:54:29+09:00
Subject: [ANN] recurrence 0.1.0

  
  git clone git://github.com/EdvardM/recurrence.git  

From the README:

* Recurrence

** Overview

Recurrence provides a simple class for handling recurring, time-associated 
objects. The goal is to create a general-purpose,
loosely coupled class library to provide common functionality for events 
occurring at predetermined intervals.

Short example:

  require 'recurrence'

  first_of_june = [2008, 6, 1] 
  r = Recurrence.new(first_of_june, :every_other => :week, :until => 
'2010-06-01')

  my_cal = MyCalendar.new_default
  my_cal.each_day { |date|
    time = Time.parse(date) # assuming date can be parsed with Time.parse
    puts 'Yay! today is the day!' if r.recurs_on?(time)
  }

** Set-like operations

Real power of Recurrence lies in it's support for set-like operations +join+, 
+intersect+, +diff+ and +complement+. For example, 
given the start date of 2008-06-01, recur something every thursday and friday:

  require 'recurrence'

  start_date = '2008-06-01'
  r1 = Recurrence.new(start_date, :every => :thursday)
  r2 = Recurrence.new(start_date, :every => :friday)
  r = r1.join(r2)

Another example, a tad contrived perhaps: 

  # Recur something every friday, except if it is last friday of the month:

  dow = :friday
  r1 = Recurrence.new(:epoch, :every => dow)
  r2 = Recurrence.new(:epoch, :every_last => dow, :of => :month)

  r = r1.diff(r2)

Nested set-like operations are also possible. So, for arbitrary recurrences a 
and b and any time t, the following should always apply:

  r1 = (a.join(b)).complement
  r2 = (a.complement).intersect(b.complement) 

  r1.recurs_on?(t) == r2.recurs_on?(t) # De Morgan's law - complement of a 
union is the same as intersection of the complements

See RecurrenceBase::SetOperations for more.

** Installation

Enter

  rake gem
  
on the command line in the same directory as this README file, it should 
produce the gem under the pkg directory.
Then you should be able to say

  sudo gem install pkg/recurrence*.gem
  
to install the gem to your local system.

KTHXBAI
  
** License

MIT (see MIT-LICENSE)

-- 
# Ed

-- 
# Edvard
# I do know everything, just not all at once. It's a virtual memory problem.