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@santosh79
Created November 17, 2009 18:06
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DSL form of memoizer
module Memoize
def remember(method, &block)
define_method(method, block)
original_method = instance_method(method)
define_method(method) do |*args|
@memory ||= {}
bound_method = original_method.bind(self)
@memory[args] = bound_method.call(args) unless @memory.has_key?(args)
@memory[args]
end
end
end
class Discounter
extend Memoize
remember :discount do |*skus|
expensive_calc(skus)
end
private
def expensive_calc(*skus)
puts "in expensive calc for #{skus}"
skus.inject{|m,n| m + n}
end
end
d = Discounter.new
d.discount(1,2,3)
d.discount(1,2,3)
d.discount(4,2,3)
d.discount(4,2,3)
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