From: James Gray <james@...>
Date: 2008-10-29T02:58:12+09:00
Subject: Re: memoization example the ruby programming language question

On Oct 28, 2008, at 11:32 AM, Hiro Protagonist wrote:

> Hi all,

Hello.

> Attached is the example of memoization from the above book.

> I marked the line that I don't understand.  I want an explanation in
> terms of syntax.

OK, lambda() is just the tool that creates the Proc object for you.   
You call memoize() on that to turn it into a meomized Proc.

> If cache has data why is method memoize called first?

The memoize() method is called on a Proc, to transform it into a  
memoized Proc.  From then on, you get the cached magic when you use it.

> This example may use some ruby 1.9 syntax.  I think factorial[x-1]  
> is equivalent to factorial.call(x-1).

That's valid in Ruby 1.8 as well.

Hope that helps explain things.

James Edward Gray II