From: Dave Thomas <Dave@...>
Date: 2001-01-04T05:20:23+09:00
Subject: [ruby-talk:8590] Re: bug??

jmichel@schur.institut.math.jussieu.fr (Jean Michel) writes:

> Is there any way to get the perl behaviour?

That's what the new block syntax does, but in a general manner.

  h = Hash.new {block}

will execute block whenever an element with no key is accessed,
storing the result back in the hash at that key, so

  h = Hash.new {|h,k| h[k] = Array.new}

will automatically create an array for any uninitialized hash reference, 
and

 h = Hash.new { raise 'go away' }

will prevent you from accessing unset entries.

You could also use this scheme to implement the equivalent of ties and 
so on.


Regards


Dave