From: yamlrb@...
Date: 2002-08-30T02:21:11+09:00
Subject: [ANN] YAML.rb 0.40 -- Circular references, Emitter enhancements

Aha!  A new YAML.rb is out at long last: >

  YAML is a structured data format.  You may have used Wiki?  Well, Wiki is
  a powerful alternative to HTML.  In many ways, YAML is an alternative to
  XML.  You can represent almost any Ruby object in YAML.

Some good places to start learning are:

  - The YAML Cookbook: http://yaml4r.sf.net/cookbook/
  - YAML.rb now has CHM help: http://prdownloads.sourceforge.net/yaml4r/yamlrb-0.39.chm
  - "Look Ma, No Tags": http://www.xml.com/pub/a/2002/07/24/yaml.html

About the new release: >

  The new YAML.rb 0.40 now handles references in emitting (including circular
  references).  This release also introduces numerous enhancements and fixes
  to the Emitter class.  Thanks to Tom Sawyer for a number of bug reports.
  
  The latest release also adds convenient methods for adding your own custom
  to_yaml methods to your classes.  For example, if you have an object and
  you want to organize its properties in a specific order:
  
      class MouseMan
        attr_accessor :name, :cape, :length_of_tail
        def to_yaml( opts = {} )
          YAML::quick_emit( self.id, opts ) { |out|
            out.map( "!ruby/object:MouseMan" ) { |map|
              [:name, :cape, :length_of_tail].each { |p|
                map.add( p.id2name, self.send( p ) )
              }
            }
          }
        end
      end 
  
      mm = MouseMan.new
      mm.name = "Zipper"
      mm.cape = true
      mm.length_of_tail = "1.45 cm"
  
      puts mm.to_yaml
      # (prints)
      #    --- !ruby/object:MouseMan
      #    name: Zipper
      #    cape: (true)
      #    length_of_tail: 1.45 cm
  
  So, there are basically Emitter#map and Emitter#seq methods for
  controlling how you output those constructs.

This document is also valid YAML!: >

  Try copying and pasting it into IRB, like:

    txt =<<EOY
    # .. paste in here ..
    EOY
    ann = YAML::load( txt )

  Then, access the 'ann' variable.  Should be a Ruby Hash!

  YAML.rb is available at http://yaml4r.sf.net/

  _why