dirty-memoize

= dirty-memoize

• http://github.com/clbustos/dirty-memoize

== DESCRIPTION

Like Memoize, but designed for mutable and parametizable objects

Use when:

• You have one expensive method (\compute) which set many internal variables. So, is preferable lazy evaluation of these dependent variables.
• The expensive operation depends on one or more parameters
• Changes on one or more parameters affect all dependent variables
• You may want to hide the call of 'compute' operation
• The user could want test several different parameters values

== SYNOPSIS

By default, the method to compute should be called #compute. Set constant DIRTY_COMPUTE to the name of other method if you need it

Example:

require 'dirty-memoize'

class Factorial
include DirtyMemoize
attr_reader :result
attr_writer :n
dirty_memoize :result
dirty_writer :n

def initialize
@n=nil
@result=nil
end
def fact(n)
return 1 if n==1
n*(fact(n-1))
end
def compute
puts "Computing the factorial!"
@result=fact(@n)
end
end

a=Factorial.new
a.n=10
puts "Our object is dirty: #{a.dirty?}"
puts "The result is: #{a.result}"
puts "Our object is no longer dirty: #{a.dirty?}"
puts "And the result is cached without calling the compute method: #{a.result}"
puts "Now, n is changed to 5"
a.n=5
# Object is now dirty. So, compute will be called when we get result
puts "The result is: #{a.result}"

== Sugestions

• Fork, modify and do wathever you need with it.

== Copyright

Copyright (c) 2010-2011 Claudio Bustos. See LICENSE for details.