From: Jim Weirich <jim@...>
Date: 2004-12-05T09:03:39+09:00
Subject: Re: Using yield

On Saturday 04 December 2004 05:44 pm, Bill Kelly wrote:
> My most recent use of yield is in a tree-structured database,
> where I wanted to be able to perform {some operation} on a
> node and all its children. �So,
>
> � def apply_all(&block)
> � � yield self
> � � @children.each_value {|n| n.apply_all(&block) } if @children
> � end

This is a very common use of blocks.  You might consider the following 
modification, it may (or may not) be useful in your application.

Change the name of "apply_all" to "each", and then include the module 
Enumerable into your class.  Then you can do things like (assuming "name" 
might be a method on your node) ....

    some_node.collect { |n| n.name } # Get a list of all the names
    some_node.find { |n| n.name =~ /^Bill/ }  # Find a matching node

-- 
-- Jim Weirich    jim@weirichhouse.org     http://onestepback.org
-----------------------------------------------------------------
"Beware of bugs in the above code; I have only proved it correct, 
not tried it." -- Donald Knuth (in a memo to Peter van Emde Boas)