EdvardM
9/4/2008 5:13:00 AM
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)
--
# Edvard
# I do know everything, just not all at once. It's a virtual memory
problem.