Added a handy convenience method for directly modifying an existing p…

…list.

lib/plist/parser.rb

@@ -28,6 +28,15 @@ def Plist::parse_xml( filename_or_xml )
     parser.parse
     listener.result
   end
+
+  # Parses and yields the plist as a hash, and
+  # commits changes back to the original file (destructive)
+  def self.modify(path, &block)
+    if plist = Plist::parse_xml(path)
+      yield plist if block_given?
+      Plist::Emit.save_plist(plist, path)
+    end
+  end
 
   class Listener
     #include REXML::StreamListener

test/test_parser.rb

@@ -6,7 +6,6 @@
 ##############################################################
 
 require 'test/unit'
-
 require 'plist'
 
 class TestParser < Test::Unit::TestCase
@@ -94,7 +93,26 @@ def test_filename_or_xml_is_stringio
 
     assert_nil data
   end
+end
 
+class TestDirectModification < Test::Unit::TestCase
+
+  def setup
+    test_file = File.expand_path("assets/AlbumData.xml", File.dirname(__FILE__))
+    FileUtils.cp(test_file, 'modificationtest.plist')
+  end
+
+  def teardown
+    FileUtils.rm('modificationtest.plist')
+  end
+
+  def test_plist_modification_with_block
+    Plist.modify('modificationtest.plist') do |plist|
+      plist['Application Version'] = '10.1.2'
+    end
+    assert_equal '10.1.2', Plist.parse_xml('modificationtest.plist')['Application Version']
+  end
+
 end
 
 __END__