Recurrence 0.1.0, Ruby library for recurring stuff

Ruby
1

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)

2

On Sep 3, 2008, at 22:09 , EdvardM wrote:

time = Time.parse(date) # assuming date can be parsed with
Time.parse
puts ‘Yay! today is the day!’ if r.recurs_on?(time)
}

shorter, more efficient example:

require ‘date’

(Date.civil(2008, 6, 1)…Date.civil(2010, 6, 1)).step(14) do |d|
puts d
end

** Set-like operations

why? when would you need/want this?

** Installation

rake gem
sudo gem install pkg/recurrence*.gem

you’re forgetting about rubyforge. you really should release real gems.

3

** Set-like operations

why? when would you need/want this?

There’s a project similar to the GP’s called Runt that I used at work
for a
calendaring program. This program had to handle expressions like “every
15th and 20th business day, effective July 20th, 1987”. I used Runt’s
set-like operations for that example.

James

4

On Fri, Sep 5, 2008 at 8:51 AM, James H.
[email protected]wrote:

What I’d really love for my current project is a library for recurring
events which had the same view of how to define them as rfc 2445 a.k.a.
iCalendar

There are a couple of gems which can parse and produce iCalendar format,
but
neither of them handles the semantics of recurring events.

–
Rick DeNatale

My blog on Ruby
http://talklikeaduck.denhaven2.com/