memoize.rb in facets-2.7.0

- old
+ new
@@ -1,113 +2 @@
-# = Memoize
-#
-# 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(1)
-#   t.a.__id__ == t.a.__id__  #=> true
-#
-# == Authors
-#
-# * trans
-# * rtb
-#
-# == Copying
-#
-# Copyright (c) 2005 Robert Feldt
-#
-# Ruby License
-#
-# This module is free software. You may use, modify, and/or redistribute this
-# software under the same terms as Ruby.
-#
-# This program is distributed in the hope that it will be useful, but WITHOUT
-# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
-# FOR A PARTICULAR PURPOSE.
-
-#require 'facets/memoizer'
-
-#
-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)
-    meths.each do |meth|
-      old = instance_method(meth)
-      new = proc do |*args|
-        mc = ((@_MEMOIZE_CACHE ||= {})[meth] ||= {})
-        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.
-def memoize(*args)
-  Object.memoize(*args)
-end
-
-module Kernel #:nodoc:
-
-  # Object#cache is essentially like Module#memoize except
-  # it can also be used on singleton/eigen methods.
-  # OTOH, memoize's implementation is arguably better for it's
-  # use of #bind instead of #alias. Eventually the two implmenations
-  # should be reconciled with a single implementation.
-  #
-  def cache m = nil
-    if m
-      (Module === self ? self : (class << self; self; end)).module_eval <<-code
-        alias_method '__#{ m }__', '#{ m }'
-        def #{ m }(*__a__,&__b__)
-          c = cache['#{ m }']
-          k = [__a__,__b__]
-          if c.has_key? k
-            c[k]
-          else
-            c[k] = __#{ m }__(*__a__,&__b__)
-          end
-        end
-      code
-    end
-    @cache ||= Hash::new{|h,k| h[k]={}}
-  end
-
-end
-
+require 'facets/once'