From: Kirk Haines <khaines@...>
Date: 2005-10-02T00:18:15+09:00
Subject: Re: Lazy evaluaton (was Re: In your opinion....)

On Saturday 01 October 2005 8:47 am, Kirk Haines wrote:

> In the original example, it illustrated how, because lambdas implement #[],
> one could have either a memoizing or a nonmeoizing FUN[] depending on a
> configuration value.

To followup:

def create_calculator_object(memoize, &b)
  memoize ? Hash.new {|h,k| puts "memoizing #{k}"; h[k] = b.call(k)} : b
end

a = create_calculator_object(true) {|k| (k * 10000007) % 20}
b = create_calculator_object(false) {|k| (k * 10000007) % 20}

irb(main):007:0> a[5]
memoizing 5
=> 15
irb(main):008:0> a[5]
=> 15
irb(main):009:0> b[5]
=> 15


Kirk Haines