class Module

def __memoize_cache__

method call results.
Returns the current memoize cache for all the stored objects and 
def __memoize_cache__
  @__memoize_cache__ ||= {}
end

def __memoize_cache__

Returns the current memoize cache for this Module. 
def __memoize_cache__
  @__memoize_cache__
end

def __memoize_cache_delete__

Finalizer to delete the stored result for a garbage collected object. 
def __memoize_cache_delete__
  lambda do |id|
    $DEBUG and warn "Deleted method results for object id='#{id}'"
    __memoize_cache__.delete(id)
  end
end

def memoize_function(*function_ids)

function.
memoized result does ONLY depend on the arguments given to the
Automatically memoize calls of the functions +function_ids+. The 
def memoize_function(*function_ids)
  mc = @__memoize_cache__ ||= {}
  function_ids.each do |method_id|
    orig_method = instance_method(method_id)
    __send__(:define_method, method_id) do |*args|
      if mc.key?(args)
        result = mc[args]
      else
        result = mc[args] = orig_method.bind(self).call(*args)
        if $DEBUG
          warn "#{self.class} cached function #{method_id}(#{args.inspect unless args.empty?}) = #{result.inspect}"
        end
      end
      result
    end
  end
end

def memoize_method(*method_ids)

object the method is called on.
memoized results do NOT ONLY depend on the arguments, but ALSO on the
Automatically memoize calls of the the methods +method_ids+. The 
def memoize_method(*method_ids)
  method_ids.each do |method_id|
    orig_method = instance_method(method_id)
    __send__(:define_method, method_id) do |*args|
      unless mc = ::Module.__memoize_cache__[__id__]
        mc = ::Module.__memoize_cache__[__id__] ||= {}
        ObjectSpace.define_finalizer(self, ::Module.__memoize_cache_delete__)
      end
      if mc.key?(args)
        result = mc[args]
      else
        result = mc[args] = orig_method.bind(self).call(*args)
        if $DEBUG
          warn "#{self.class} cached method #{method_id}(#{args.inspect unless args.empty?}) = #{result.inspect} [#{__id__}]"
        end
      end
      result
    end
  end
end