From: Brian Buckley <briankbuckley@...>
Date: 2005-11-18T23:41:59+09:00
Subject: Re: YAML and constant objects

> > I don't yet fully understand your code

I am posting the solution I came up with, seeking critical commentary.
 In particular I am unsure whether my use of YAML's "add_domain_type"
(where I've got a separate entry for each constant X for which
"X.yamlize_as_constant" is called) is in the spirit of how YAML was
designed to be used.

Any comments appreciated.

--Brian Buckley

module YamlizeAsConstant
  def yamlize_as_constant(name = nil, domain = "aw.com,2005")
    name = (self.class.name + "/" + constant_name).downcase if !name
    yaml_name = "!" + domain + "/" + name
     (class << self; self; end).class_eval do
      define_method("to_yaml_type") {|*args| yaml_name}
      define_method("to_yaml_properties"){|*args| []}    #no
properties saved
    end
    #don't make an new object, rather return the constant
    YAML.add_domain_type(domain, name) {|type, val| self}
  end

  def constant_name
    self.class.constants.each do |c|
      return c if self.class.const_get(c) == self
    end
    nil
  end

end

class Object
  include YamlizeAsConstant
end

class Foo
  attr_accessor :a, :b # many more
  FOO1 = Foo.new
  FOO1.a = "test text a"
  FOO1.b = "test text b"
  FOO1.yamlize_as_constant
end

class TestYamlizeAsConstant < Test::Unit::TestCase
  def test_foo
    assert_equal "--- !aw.com,2005/foo/foo1 {}", Foo::FOO1.to_yaml
    assert_same Foo::FOO1, YAML::load(Foo::FOO1.to_yaml)
  end
end