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$:.unshift(File.expand_path(File.dirname(__FILE__)+"/../lib"))
# This example shows the use of dirty_memoize with dirty_writer.
# When we call the method marked with dirty_memoize on a dirty object,
# compute method is called.
# Setting a value on a dirty_writer set the object to dirty
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}"
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