From: James Gray <james@...>
Date: 2008-10-14T04:42:59+09:00
Subject: Re: status of cache in Memoizable

On Oct 13, 2008, at 2:17 PM, matt neuburg wrote:

> There's one thing happening here I don't understand. Let's say you  
> don't
> supply a value for the "cache" parameter. So the cache is simply
> Hash.new. But where does this Hash.new live? It isn't assigned to a
> variable name so what keeps it alive? It works, but how?

That variable is kept alive thanks to the magic of closures.  The  
block passed to define_method() references the variable, so it will  
exist as long as that closure does.  Think of it as private storage  
that only that block uses.

James Edward Gray II