From: Gregory Brown <gregory.t.brown@...>
Date: 2005-11-22T04:36:28+09:00
Subject: Re: Problem with Pickaxe and Yaml

On 11/21/05, Mark Haliday <markhaliday@yahoo.com> wrote:
> I've got the Pickaxe book (2nd edition) and was doing some of the Yaml
> code on page 417.  I cannot seem to get the expected results.
>
> Example:
>
> require 'yaml'
>
> class Special
>
>     def initialize(valuable, volatile, precious)
>         @valuable = valuable
>         @volatile = volatile
>         @precious = precious
>     end
>
>     def to_yaml_properties
>         %w{@precious @valuable}
>     end
>
>     def to_s
>         "#@valuable #@volatile #@precious"
>     end
> end
>
> obj = Special.new("Hello", "there", "world")
> data = YAML.dump(obj)
> obj = YAML.load(data)
>
> puts obj["valuable"]
>
> The last line throws an error, shouldn't it print out the value for
> "valuable"?

no... obj becomes an instance of class Special, and acts just like the
object before you dumped it.

greg@oracle ~ $ irb
irb(main):001:0> class Foo
irb(main):002:1> def bar
irb(main):003:2> puts "hello"
irb(main):004:2> end
irb(main):005:1> end
=> nil
irb(main):006:0> a = Foo.new
=> #<Foo:0xb7d76310>
irb(main):008:0> require "yaml"
=> true
irb(main):009:0> data = YAML.dump(a)
=> "!ruby/object:Foo {}\n\n"
irb(main):010:0> b = YAML.load(data)
=> #<Foo:0xb7c253f4>
irb(main):011:0> b.bar
hello
=> nil