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Contents
#--
# Credit goes to Robert Feldt.
#++
class Module
# Directive for making your functions faster by trading
# space for time. When you "memoize" a method/function
# its results are cached so that later calls with the
# same arguments returns results in the cache instead
# of recalculating them.
#
# class T
# def initialize(a)
# @a = a
# end
# def a
# "#{@a ^ 3 + 4}"
# end
# memoize :a
# end
#
# t = T.new
# t.a.__id__ == t.a.__id__ #=> true
#
def memoize(*meths)
@_MEMOIZE_CACHE ||= Hash.new
meths.each do |meth|
mc = @_MEMOIZE_CACHE[meth] = Hash.new
old = instance_method(meth)
new = proc do |*args|
if mc.has_key? args
mc[args]
else
mc[args] = old.bind(self).call(*args)
end
end
send(:define_method, meth, &new)
end
end
end
# This allows memoize to work in main and instance scope too.
#--
# Would this be good to have? Will need to modify for instance level, if so.
#++
#def memoize(*args)
# self.class.memoize(*args)
#end
# _____ _
# |_ _|__ ___| |_
# | |/ _ \/ __| __|
# | | __/\__ \ |_
# |_|\___||___/\__|
#
=begin test
require 'test/unit'
class T
def initialize(a)
@a = a
end
def a
"#{@a ^ 3 + 4}"
end
memoize :a
end
# test
class TC_Memoize < Test::Unit::TestCase
def setup
@t = T.new(2)
end
def test_memoize_01
assert_equal( @t.a, @t.a )
end
def test_memoize_02
assert_equal( @t.a.__id__, @t.a.__id__ )
end
def test_memoize_03
assert_equal( @t.a.__id__, @t.a.__id__ )
end
end
=end
Version data entries
20 entries across 20 versions & 1 rubygems