From: Sean O'Halpin <sean.ohalpin@...>
Date: 2005-10-18T06:48:02+09:00
Subject: Re: declaratively caching results of a method

On 10/17/05, Daniel Berger <djberg96@gmail.com> wrote:
> Jeff Wood wrote:
> > if you look at the examples ... normally you include the Memoize
> > functionality in your class
> >
> > class Foo
> >   include Memoize
> >
> >   def calc1( *args )
> >     # do something here
> >   end
> >
> >   memoize :calc1
> > end
> >
> > f = Foo.new
> > f.calc1( 1,2,3 )
> > f.calc1( 1,2,3 )
> > f.calc1( 7,8,9 )
>
> This won't work: "undefined method `memoize' for Foo:Class
> (NoMethodError)"

Here's one way to do it:

class Foo
  include Memoize
  def initialize
    memoize :foo
  end
  def foo(*args)
    puts "calculating foo(#{args.map{|x| x.inspect}.join(',')})"
    args.inject(0) {|sum, x| sum + x}
  end
end

f = Foo.new
puts f.foo(2)
puts f.foo(2)
__END__
calculating foo(2)
2

Regards,

Sean