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@santosh79
Created November 17, 2009 06:32
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memoizing on object level
class Discounter
def discount(*skus)
expensive_calc(skus)
end
private
def expensive_calc(*skus)
puts "in expensive calc for #{skus}"
skus.inject{|m,n| m + n}
end
end
def memoize(obj, method)
ghost = class << obj ; self; end
ghost.class_eval do
define_method(method) do |*args|
@memory ||= {}
@memory[args] = super unless @memory.has_key?(args)
@memory
end
end
end
d = Discounter.new
memoize(d, :discount)
d.discount(1,2,3)
d.discount(1,2,3)
d.discount(4,2,3)
d.discount(4,2,3)
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