From: Mauricio Fernandez <mfp@...>
Date: 2006-12-12T09:07:40+09:00
Subject: Re: Question on IO objects, initialize, and yaml

On Mon, Dec 11, 2006 at 02:43:22PM +0900, Mark Noworolski wrote:
> On 12/10/06, Eric Hodel <drbrain@segment7.net> wrote:
> >
> >Ruby and YAML provide hooks to cause things to happen when you load
> >from Marshal or YAML.  I think #initialize_copy gets called for
> >Marshal, I don't know the YAML ones, but  they should be easy to find.
> >
> I _want_ to use a built-in hook (the ruby way, if you will), if I can figure
> out which one and how to use it.
[...] 
> Now, I've experimented with initialize_copy on this code and your
> recommendation, and I cannot get it to do what I want.
> 
> Anybody got any other suggestions, or a concrete example for me?
> mark

require 'yaml'
class Foo
  def initialize
    @foo = 1
    @bar = 2
  end

  def yaml_initialize(tag, val)
  end
end

foo = Foo.new
foo                                # => #<Foo:0xa7dfe614 @bar=2, @foo=1>
YAML.load(YAML.dump(foo))          # => #<Foo:0xa7dfa6e0>

class Foo
  def yaml_initialize(tag, val) # !> method redefined; discarding old yaml_initialize
     @foo, @bar = val.values_at("foo", "bar")
  end
end

YAML.load(YAML.dump(foo))          # => #<Foo:0xa7ddcfc8 @bar=2, @foo=1>

-- 
Mauricio Fernandez  -   http://eigenclass.org   -  singular Ruby