From: why the lucky stiff <ruby-talk@...>
Date: 2002-12-12T08:56:07+09:00
Subject: Re: calling a perl script (YAML serialization?)

On Wednesday 11 December 2002 01:01 pm, Phil Tomson wrote:
> Now here's a crazy idea:  What we had some sort of Inline::Perl that used
> YAML serialization to communicate between the two sides?  There are YAML
> serialization modules for both Ruby and Perl and they could be used to
> pass objects back and forth between the two languages.  An Inline::Perl
> module would just sort of make the underlying communication between the
> two transparent.  Certainly most of the builtin types like Arrays, Hashes,
> String and FixNums would be transportable, I'm not sure how user defined
> classes would transfer, however (YAML dudes: is this feasable?)

Oh, yes.  It's the essence of YAML's existence.  User-defined classes are 
merely native types that are explicitly typed in YAML.  So this is a Ruby 
Hash in YAML:

  name: Peter Gorley
  id: 345
  email: peter.gorley@yaml.org

Perl would also load the above as a hash.  But if you suddenly wanted to use 
Ruby classes, the Hash would become typed:

  --- !!employee
  name: Peter Gorley
  id: 345
  email: peter.gorley@yaml.org

You would then write handler code to load this YAML document as a class in 
YAML.rb:

  YAML::add_private_type( 'employee' ) { |type, val|
     YAML::object_maker( EmployeeClass, val )
  }

This is just one technique, though.  There are several.  I'd check out the 
Cookbook [http://yaml4r.sf.net/cookbook/] and the YAML.rb docs 
[http://yaml4r.sf.net/doc/] for more ideas.

_why