64 lines
1.5 KiB
Ruby
64 lines
1.5 KiB
Ruby
# 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 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)}
|
|
#
|
|
# Memoizer is the work of Erik Veenstra
|
|
#
|
|
# Copyright (c) 2006 Erik Veenstra
|
|
#
|
|
# See http://javathink.blogspot.com/2008/09/what-is-memoizer-and-why-should-you.html
|
|
|
|
class Memoizer
|
|
|
|
#private :class, :clone, :display, :type, :method, :to_a, :to_s
|
|
private *instance_methods(true).select{ |m| m.to_s !~ /^__/ }
|
|
|
|
def initialize(object)
|
|
@self = object
|
|
@cache = {}
|
|
end
|
|
|
|
def __self__ ; @self ; end
|
|
|
|
# Not thread-safe! Speed is important in caches... ;]
|
|
def method_missing(method_name, *args, &block)
|
|
@cache[[method_name, args, block]] ||= @self.__send__(method_name, *args, &block)
|
|
end
|
|
|
|
#def self; @self; end
|
|
|
|
def self.cache(object)
|
|
new(object)
|
|
end
|
|
|
|
def self.uncache(cached_object)
|
|
cached_object.instance_variable_get('@self')
|
|
end
|
|
|
|
end
|