* lib/yaml.rb: use Psych if only it is loaded already.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@27257 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,4 +1,6 @@
-Thu Apr  8 11:31:37 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+Thu Apr  8 11:45:14 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* lib/yaml.rb: use Psych if only it is loaded already.
 
 	* lib/yaml.rb (YAML::EngineManager#yamler): set the result after
 	  successfully switched.

lib/yaml.rb

@@ -30,6 +30,8 @@ module YAML
   ENGINE = YAML::EngineManager.new
 end
 
+engine = (!defined?(Syck) && defined?(Psych) ? 'psych' : 'syck')
+
 module Syck
   ENGINE = YAML::ENGINE
 end
@@ -38,4 +40,4 @@ module Psych
   ENGINE = YAML::ENGINE
 end
 
-YAML::ENGINE.yamler = 'syck'
+YAML::ENGINE.yamler = engine