From: Ara.T.Howard@...
Date: 2005-05-12T03:05:29+09:00
Subject: Re: defining a custom to_yaml method to inline hashes

On Wed, 11 May 2005, Ara.T.Howard wrote:

> check out the following:
>
>
>  jib:~ > cat a.rb
>  require 'yaml'
>
>  # yaml can load inline hashes
>  inline_hash = YAML::load "--- { jid: 121, metric: started, time: 2005-05-10 
> 08:18:22.523016 }"
>
>  puts '=' * 8
>  y inline_hash
>  puts
>
>
>  # attempt to bludgeon to object into emitting in an inline fashion
>  class << inline_hash
>    def to_yaml(*a, &b)
>      '{ ' << map{|kv| kv.join(': ')}.join(', ') << ' }'
>    end
>  end
>
>  # looks good at first
>  puts '=' * 8
>  y inline_hash
>  puts
>
>  # but doesn't really work after all when part of another object
>  puts '=' * 8
>  y({'running' => inline_hash})
>  puts
>
>
>  jib:~ > ruby a.rb
>  ========
>  ---
>  time: 2005-05-10 08:18:22.523016
>  jid: 121
>  metric: started
>
>  ========
>  { time: 2005-05-10 08:18:22.523016, jid: 121, metric: started }
>
>  ========
>  ---
>  running:
>
>
> notice the second block is alright but the third is not.  i know i need to do
> something like
>
>  def to_yaml(*a, &b)
>    YAML::quick_emit(*a, &b) do |out|
>      # now what?
>    end
>  end
>
> but can't seem to find anything in the docs or samples.

this seems o.k. - can anyone verify this is an o.k. approach?

   jib:~ > cat a.rb
   require 'yaml'
   class Hash
     def yaml_inline= bool
       unless defined? @__yaml_inline_meth
         @__yaml_inline_meth =
           lambda {|opts|
             YAML::quick_emit(id, opts) {|emitter|
               emitter << '{ ' << map{|kv| kv.join ': '}.join(', ') << ' }'
             }
           }
         class << self
           def to_yaml opts = {}
             @__yaml_inline ? @__yaml_inline_meth[ opts ] : super
           end
         end
       end
       @__yaml_inline = bool
     end
   end


   hash = { 'jid' => 121, 'metric' => 'started', 'time' => '2005-05-10 08:18:22.523016' }


   y 'hash' => hash
   puts

   hash.yaml_inline = true
   y 'hash' => hash
   puts

   hash.yaml_inline = false
   y 'hash' => hash
   puts


   jib:~ > ruby a.rb
   ---
   hash:
     time: 2005-05-10 08:18:22.523016
     jid: 121
     metric: started

   ---
   hash: { time: 2005-05-10 08:18:22.523016, jid: 121, metric: started }

   ---
   hash:
     time: 2005-05-10 08:18:22.523016
     jid: 121
     metric: started


of course this only works with kvs as strings....

-a
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