From: dblack@...
Date: 2003-03-29T00:54:35+09:00
Subject: Re: Newbie question:Does Ruby have the structure of hash's array like  Perl does?

Hi --

On Fri, 28 Mar 2003, Brett H. Williams wrote:

> It looks like the block form gives you a new object each time to
> return when a key doesn't exist in the hash, but it doesn't assign
> that as the value of the key.  Is that correct?:

Yes; the default value for a hash is what you get for non-existent
keys, with no assignment implied, and the block form is just an
recent extension of that behavior.

It does lead to some interesting constructs:

  h = Hash.new { [] }
  h[1] = h[1]             # not a sight you see often!
  h[2].id == h[2].id      # false

and one of my favorites:

  h = Hash.new { raise "Access denied!" }

:-)


David

-- 
David Alan Black
home: dblack@superlink.net
work: blackdav@shu.edu
Web:  http://pirate.shu.edu/~blackdav