From: "trans.  (T. Onoma)" <transami@...>
Date: 2004-11-02T13:17:53+09:00
Subject: Re: Use yaml to store Ruby arrays or hashes in the DB?

On Monday 01 November 2004 11:01 pm, James Britt wrote:
| trans. (T. Onoma) wrote:
| > On Monday 01 November 2004 10:20 pm, James Britt wrote:
| > | How can you store Ruby-specific objects (i.e., custom, user-defined
| > | classes) in a language-neutral way?
| >
| > You use YAML.
| >
| > No really. That's all there it to it.
|
| The ri data files for 1.8.2 are in YAML.  Can I load the following into
| a YAML parser in, say, perl or python?  How does that language make
| sense of it?
|
| --- !ruby/object:RI::MethodDescription
| aliases: []
| block_params:
| comment:
|    - !ruby/struct:SM::Flow::P
|      body: "Exclusive Or---If <em>obj</em> is <tt>nil</tt> or
| <tt>false</tt>, returns <tt>false</tt>; otherwise, returns <tt>true</tt>."
| full_name: FalseClass#^
| is_singleton: false
| name: "^"
| params: >
|    false ^ obj    => true or false
|
|    nil   ^ obj    => true or false
|
| visibility: public


You'll have to use types to get rid of the !ruby/object cruft.

  YAML.add_private_type( 'MehthodDescription' ) { |type, val|
     RI::MethodDescrition.new( val )
  }

That'll load it automatically. Note that val is the parsed document (a hash) 
so your initialize method will either have to deal with that ot you'll need a 
new constructor method instead. I usually define #initialize_yaml(val) and 
use that.

To output the type correctly use:

  class RI::MethodDescription

    def to_yaml_type
      'MethodDescription'
    end

  end

Perl and Python should be able to handle no problem from there.

HTH,
T.

P.S. You can also use a Domain type if you prefer. Form ore info see: 

  http://yaml4r.sourceforge.net/doc/