1 files changed, 20 insertions, 54 deletions

diff --git a/lib/yaml.rb b/lib/yaml.rb
index 6ae71fb1dc..19df5efc53 100644
--- a/lib/yaml.rb
+++ b/lib/yaml.rb
@@ -2,75 +2,41 @@
 # The YAML module allows you to use one of the two YAML engines that ship with
 # ruby.  By default Psych is used but the old and unmaintained Syck may be
 # chosen.
-#
-# See Psych or Syck for usage and documentation.
-#
-# To set the YAML engine to syck:
-#
-#   YAML::ENGINE.yamler = 'syck'
-#
-# To set the YAML engine back to psych:
-#
-#   YAML::ENGINE.yamler = 'psych'
 
-module YAML
+begin
+  require 'psych'
+rescue LoadError
+  warn "#{caller[0]}:"
+  warn "It seems your ruby installation is missing psych (for YAML output)."
+  warn "To eliminate this warning, please install libyaml and reinstall your ruby."
+  raise
+end
+
+module Psych
   class EngineManager # :nodoc:
     attr_reader :yamler
 
     def initialize
-      @yamler = nil
+      @yamler = 'psych'
     end
 
     def syck?
-      'syck' == @yamler
+      false
     end
 
     def yamler= engine
-      raise(ArgumentError, "bad engine") unless %w{syck psych}.include?(engine)
-
-      require engine unless (engine == 'syck' ? Syck : Psych).const_defined?(:VERSION)
+      case engine
+      when 'syck' then warn "syck has been removed"
+      when 'psych' then @yamler = 'psych'
+      else
+        raise(ArgumentError, "bad engine")
+      end
 
-      ::Object.class_eval <<-eorb, __FILE__, __LINE__ + 1
-        remove_const 'YAML'
-        YAML = #{engine.capitalize}
-        remove_method :to_yaml
-        alias :to_yaml :#{engine}_to_yaml
-      eorb
-
-      @yamler = engine
       engine
     end
   end
 
-  ##
-  # Allows changing the current YAML engine.  See YAML for details.
-
-  ENGINE = YAML::EngineManager.new
-end
-
-if defined?(Psych)
-  engine = 'psych'
-elsif defined?(Syck)
-  engine = 'syck'
-else
-  begin
-    require 'psych'
-    engine = 'psych'
-  rescue LoadError
-    warn "#{caller[0]}:"
-    warn "It seems your ruby installation is missing psych (for YAML output)."
-    warn "To eliminate this warning, please install libyaml and reinstall your ruby."
-    require 'syck'
-    engine = 'syck'
-  end
-end
-
-module Syck
-  ENGINE = YAML::ENGINE
-end
-
-module Psych
-  ENGINE = YAML::ENGINE
+  ENGINE = EngineManager.new # :nodoc:
 end
 
-YAML::ENGINE.yamler = engine
+YAML = Psych