* ext/psych/lib/psych.rb: Syck api compatibility [ruby-core:29157]

* ext/psych/lib/psych/nodes/node.rb: ditto
* test/psych/test_psych.rb: ditto

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@27134 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 6 insertions, 4 deletions

diff --git a/ext/psych/lib/psych/nodes/node.rb b/ext/psych/lib/psych/nodes/node.rb
index 0de768c7ac..3ab9acae43 100644
--- a/ext/psych/lib/psych/nodes/node.rb
+++ b/ext/psych/lib/psych/nodes/node.rb
@@ -30,10 +30,12 @@ module Psych
       # Convert this node to YAML.
       #
       # See also Psych::Visitors::Emitter
-      def to_yaml
-        io = StringIO.new
-        Visitors::Emitter.new(io).accept self
-        io.string
+      def to_yaml io = nil
+        real_io = io || StringIO.new
+
+        Visitors::Emitter.new(real_io).accept self
+        return real_io.string unless io
+        io
       end
     end
   end