Module: Decorate::Memoize

Defined in:
lib/decorate/memoize.rb

Class Method Summary collapse

Class Method Details

.memoize ⇒ Object

A naive memoization decorator, using a plain Hash as cache.

Example usage:

require "decorate/memoize"

Decorate::Memoize.memoize
def factorial(n)
  n == 0 ? 1 : n * factorial(n - 1)
end
factorial(7) # => 5040

Memoization takes the arguments as well as the instance itself into account. You can also extend a module/class with Decorate::Memoize to leave off the module prefix. Note that this decorator doesn’t work for methods that take a block.



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# File 'lib/decorate/memoize.rb', line 22

def memoize
  Decorate.decorate { |klass, method_name|
    wrapped_method_name = Decorate.create_alias(klass, method_name, :memoize)
    # TODO: should use weak hash tables
    cache = Hash.new { |hash, key| hash[key] = {} }
    klass.send(:define_method, method_name) { |*args|
      icache = cache[self]
      if icache.has_key?(args)
        icache[args]
      else
        icache[args] = send(wrapped_method_name, *args)
      end
    }
  }
end