return yamler to original state after fussing with it

lib/new_relic/control/instance_methods.rb

@@ -1,5 +1,9 @@
+require 'new_relic/language_support'
+
 module NewRelic
   class Control
+    include NewRelic::LanguageSupport::Control
+
     # Contains methods that relate to the runtime usage of the control
     # object. Note that these are subject to override in the
     # NewRelic::Control::Framework classes that are actually instantiated
@@ -147,15 +151,18 @@ def initialize local_env, config_file_override=nil
           puts "Cannot find or read #{newrelic_file}"
           @yaml = {}
         else
-          YAML::ENGINE.yamler = 'syck' if defined?(YAML::ENGINE)
-          @yaml = YAML.load(ERB.new(File.read(newrelic_file)).result(binding))
+          @yaml = load_newrelic_yml(newrelic_file, binding)
         end
       rescue ScriptError, StandardError => e
         puts e
         puts e.backtrace.join("\n")
         raise "Error reading newrelic.yml file: #{e}"
       end
 
+      def load_newrelic_yml(path, binding)
+        YAML.load(ERB.new(File.read(path)).result(binding))
+      end
+
       def root
         '.'
       end

lib/new_relic/language_support.rb

@@ -14,7 +14,24 @@ def self.load(*args)
       end
     end
   end
-
+
+  module Control
+    def self.included(base)
+      # need to use syck rather than psych when possible
+      if defined?(::YAML::ENGINE)
+        base.class_eval do
+          def load_newrelic_yml(*args)
+            yamler = ::YAML::ENGINE.yamler
+            ::YAML::ENGINE.yamler = 'syck'
+            val = super
+            ::YAML::ENGINE.yamler = yamler
+            val
+          end
+        end
+      end
+    end
+  end
+
   module SynchronizedHash
     def self.included(base)
       # need to lock iteration of stats hash in 1.9.x