Memoizer

Synopsis

Memoizer wraps objects to provide cached method calls.

  class X
    def initialize ; @tick = 0 ; end
    def tick; @tick + 1; end
    def memo; @memo ||= Memoizer.new(self) ; end
  end

  x = X.new
  x.tick       #=> 1
  x.memo.tick  #=> 2
  x.tick       #=> 3
  x.memo.tick  #=> 2
  x.tick       #=> 4
  x.memo.tick  #=> 2

You can also use to cache a collections of objects to gain code speed ups.

  points = points.collect{|point| Memoizer.cache(point)}

After our algorithm has finished using points, we want to get rid of these Memoizer objects. That‘s easy:

   points = points.collect{|point| point.self }

Or if you prefer (it is ever so slightly safer):

   points = points.collect{|point| Memoizer.uncache(point)}

References

See javathink.blogspot.com/2008/09/what-is-memoizer-and-why-should-you.html

Authors

Erik Veenstra
Thomas Sawyer

Copying

Methods

cache method_missing new self uncache

Public Class methods

cache(object)

[ + ]

# File lib/more/facets/memoizer.rb, line 65
  def self.cache(object)
    new(object)
  end

new(object)

[ + ]

# File lib/more/facets/memoizer.rb, line 53
  def initialize(object)
    @self  = object
    @cache = {}
  end

uncache(cached_object)

[ + ]

# File lib/more/facets/memoizer.rb, line 69
  def self.uncache(cached_object)
    cached_object.self
  end

Public Instance methods

method_missing(method_name, *args, &block)

[ + ]

# File lib/more/facets/memoizer.rb, line 58
  def method_missing(method_name, *args, &block)
    # Not thread-safe! Speed is important in caches... ;]
    @cache[[method_name, args, block]] ||= @self.__send__(method_name, *args, &block)
  end

self()

[ + ]

# File lib/more/facets/memoizer.rb, line 63
  def self; @self; end