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# encoding: utf-8
module Nanoc
# Adds support for memoizing functions.
#
# @since 3.2.0
module Memoization
# Memoizes the method with the given name. The modified method will cache
# the results of the original method, so that calling a method twice with
# the same arguments will short-circuit and return the cached results
# immediately.
#
# Memoization assumes that the current object as well as the function
# arguments are immutable. Mutating the object or the arguments will not
# cause memoized methods to recalculate their results. There is no way to
# un-memoize a result, and calculation results will remain in memory even
# if they are no longer needed.
#
# @example A fast fib function due to memoization
#
# class FibFast
#
# extend Nanoc::Memoization
#
# def run(n)
# if n == 0
# 0
# elsif n == 1
# 1
# else
# run(n-1) + run(n-2)
# end
# end
# memoize :run
#
# end
#
# @param [Symbol, String] method_name The name of the method to memoize
#
# @return [void]
def memoize(method_name)
# Alias
original_method_name = '__nonmemoized_' + method_name.to_s
alias_method original_method_name, method_name
# Redefine
define_method(method_name) do |*args|
# Get cache
@__memoization_cache ||= {}
@__memoization_cache[method_name] ||= {}
# Recalculate if necessary
if !@__memoization_cache[method_name].key?(args)
result = send(original_method_name, *args)
@__memoization_cache[method_name][args] = result
end
# Done
@__memoization_cache[method_name][args]
end
end
end
end
Version data entries
8 entries across 8 versions & 1 rubygems