From: Sean O'Halpin <sean.ohalpin@...>
Date: 2005-10-18T06:51:28+09:00
Subject: Re: declaratively caching results of a method

On 10/17/05, Sean O'Halpin <sean.ohalpin@gmail.com> wrote:
> 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
>
I should have pointed out that this method only memoizes within the
instance... Another instance of Foo won't get the benefit of the
memoization.

Sean