* lib/rss, test/rss, sample/rss: backported from CVS HEAD.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_8@7509 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

15 files changed, 1232 insertions, 593 deletions

diff --git a/lib/rss/0.9.rb b/lib/rss/0.9.rb
index c772e80870..797a46ca3b 100644
--- a/lib/rss/0.9.rb
+++ b/lib/rss/0.9.rb
@@ -60,17 +60,14 @@ module RSS
     end
     
     def to_s(convert=true, indent=calc_indent)
-      next_indent = indent + INDENT
-      rv = <<-EOR
-#{xmldecl}
-#{xml_stylesheet_pi}
-#{indent}<rss version="#{@rss_version}"#{ns_declaration(next_indent)}>
-#{channel_element(false, next_indent)}
-#{other_element(false, next_indent)}
-#{indent}</rss>
-EOR
+      rv = tag(indent, ns_declarations) do |next_indent|
+        [
+          channel_element(false, next_indent),
+          other_element(false, next_indent),
+        ]
+      end
       rv = @converter.convert(rv) if convert and @converter
-      remove_empty_newline(rv)
+      rv
     end
 
     private
@@ -86,7 +83,7 @@ EOR
 
     def _attrs
       [
-        ["version", true],
+        ["version", true, "rss_version"],
       ]
     end
 
@@ -104,8 +101,6 @@ EOR
         ["webMaster", "?"],
         ["rating", "?"],
         ["docs", "?"],
-        ["skipDays", "?"],
-        ["skipHours", "?"],
       ].each do |x, occurs|
         install_text_element(x)
         install_model(x, occurs)
@@ -120,6 +115,8 @@ EOR
       end
 
       [
+        ["skipDays", "?"],
+        ["skipHours", "?"],
         ["image", nil],
         ["textInput", "?"],
       ].each do |x, occurs|
@@ -146,35 +143,35 @@ EOR
       end
 
       def to_s(convert=true, indent=calc_indent)
-        next_indent = indent + INDENT
-        rv = <<-EOT
-#{indent}<channel>
-#{title_element(false, next_indent)}
-#{link_element(false, next_indent)}
-#{description_element(false, next_indent)}
-#{language_element(false, next_indent)}
-#{copyright_element(false, next_indent)}
-#{managingEditor_element(false, next_indent)}
-#{webMaster_element(false, next_indent)}
-#{rating_element(false, next_indent)}
-#{pubDate_element(false, next_indent)}
-#{lastBuildDate_element(false, next_indent)}
-#{docs_element(false, next_indent)}
-#{skipDays_element(false, next_indent)}
-#{skipHours_element(false, next_indent)}
-#{image_element(false, next_indent)}
-#{item_elements(false, next_indent)}
-#{textInput_element(false, next_indent)}
-#{other_element(false, next_indent)}
-#{indent}</channel>
-EOT
+        rv = tag(indent) do |next_indent|
+          [
+            title_element(false, next_indent),
+            link_element(false, next_indent),
+            description_element(false, next_indent),
+            language_element(false, next_indent),
+            copyright_element(false, next_indent),
+            managingEditor_element(false, next_indent),
+            webMaster_element(false, next_indent),
+            rating_element(false, next_indent),
+            pubDate_element(false, next_indent),
+            lastBuildDate_element(false, next_indent),
+            docs_element(false, next_indent),
+            cloud_element(false, next_indent),
+            skipDays_element(false, next_indent),
+            skipHours_element(false, next_indent),
+            image_element(false, next_indent),
+            item_elements(false, next_indent),
+            textInput_element(false, next_indent),
+            other_element(false, next_indent),
+          ]
+        end
         rv = @converter.convert(rv) if convert and @converter
         rv
       end
 
       private
       def children
-        [@image, @textInput, @cloud, *@item]
+        [@skipDays, @skipHours, @image, @textInput, @cloud, *@item]
       end
 
       def _tags
@@ -206,6 +203,121 @@ EOT
         rv
       end
 
+      def maker_target(maker)
+        maker.channel
+      end
+
+      def setup_maker_elements(channel)
+        super
+        [
+          [skipDays, "day"],
+          [skipHours, "hour"],
+        ].each do |skip, key|
+          if skip
+            skip.__send__("#{key}s").each do |val|
+              target_skips = channel.__send__("skip#{key.capitalize}s")
+              new_target = target_skips.__send__("new_#{key}")
+              new_target.content = val.content
+            end
+          end
+        end
+      end
+
+      class SkipDays < Element
+        include RSS09
+
+        [
+          ["day", "*"]
+        ].each do |x, occurs|
+          install_have_children_element(x)
+          install_model(x, occurs)
+        end
+
+        def to_s(convert=true, indent=calc_indent)
+          rv = tag(indent) do |next_indent|
+            [
+              day_elements(false, next_indent)
+            ]
+          end
+          rv = @converter.convert(rv) if convert and @converter
+          rv
+        end
+
+        private
+        def children
+          @day
+        end
+
+        def _tags
+          @day.compact.collect do
+            [nil, "day"]
+          end
+        end
+
+        class Day < Element
+          include RSS09
+
+          content_setup
+
+          def initialize(content=nil)
+            super()
+            @content = content
+          end
+      
+        end
+        
+      end
+      
+      class SkipHours < Element
+        include RSS09
+
+        [
+          ["hour", "*"]
+        ].each do |x, occurs|
+          install_have_children_element(x)
+          install_model(x, occurs)
+        end
+
+        def to_s(convert=true, indent=calc_indent)
+          rv = tag(indent) do |next_indent|
+            [
+              hour_elements(false, next_indent)
+            ]
+          end
+          rv = @converter.convert(rv) if convert and @converter
+          rv
+        end
+
+        private
+        def children
+          @hour
+        end
+
+        def _tags
+          @hour.compact.collect do
+            [nil, "hour"]
+          end
+        end
+
+        class Hour < Element
+          include RSS09
+
+          content_setup
+
+          def initialize(content=nil)
+            super()
+            @content = content
+          end
+
+          remove_method :content=
+          def content=(value)
+            @content = value.to_i
+          end
+          
+        end
+        
+      end
+      
       class Image < Element
 
         include RSS09
@@ -220,19 +332,18 @@ EOT
         end
 
         def to_s(convert=true, indent=calc_indent)
-          next_indent = indent + INDENT
-          rv = <<-EOT
-#{indent}<image>
-#{url_element(false, next_indent)}
-#{title_element(false, next_indent)}
-#{link_element(false, next_indent)}
-#{width_element(false, next_indent)}
-#{height_element(false, next_indent)}
-#{description_element(false, next_indent)}
-#{other_element(false, next_indent)}
-#{indent}</image>
-EOT
-       		rv = @converter.convert(rv) if convert and @converter
+          rv = tag(indent) do |next_indent|
+            [
+              url_element(false, next_indent),
+              title_element(false, next_indent),
+              link_element(false, next_indent),
+              width_element(false, next_indent),
+              height_element(false, next_indent),
+              description_element(false, next_indent),
+              other_element(false, next_indent),
+            ]
+          end
+          rv = @converter.convert(rv) if convert and @converter
     	    rv
         end
 
@@ -244,8 +355,12 @@ EOT
             [nil, elem]
           end
         end
+
+        def maker_target(maker)
+          maker.image
+        end
       end
-      
+
       class Cloud < Element
 
         include RSS09
@@ -270,16 +385,8 @@ EOT
         end
 
         def to_s(convert=true, indent=calc_indent)
-          next_indent = indent + INDENT
-          rv = <<-EOT
-#{indent}<cloud
-#{next_indent}domain="#{h @domain}"
-#{next_indent}port="#{h @port}"
-#{next_indent}path="#{h @path}"
-#{next_indent}registerProcedure="#{h @registerProcedure}"
-#{next_indent}protocol="#{h @protocol}"/>
-EOT
-       		rv = @converter.convert(rv) if convert and @converter
+          rv = tag(indent)
+          rv = @converter.convert(rv) if convert and @converter
     	    rv
         end
 
@@ -300,15 +407,21 @@ EOT
           install_text_element(x)
         end
 
-        %w(category source enclosure).each do |x|
+        %w(source enclosure).each do |x|
           install_have_child_element(x)
         end
 
         [
+          %w(category categories),
+        ].each do |name, plural_name|
+          install_have_children_element(name, plural_name)
+        end
+        
+        [
           ["title", '?'],
           ["link", '?'],
           ["description", '?'],
-          ["category", '?'],
+          ["category", '*'],
           ["source", '?'],
           ["enclosure", '?'],
         ].each do |tag, occurs|
@@ -316,36 +429,51 @@ EOT
         end
 
         def to_s(convert=true, indent=calc_indent)
-          next_indent = indent + INDENT
-          rv = <<-EOT
-#{indent}<item>
-#{title_element(false, next_indent)}
-#{link_element(false, next_indent)}
-#{description_element(false, next_indent)}
-#{category_element(false, next_indent)}
-#{source_element(false, next_indent)}
-#{enclosure_element(false, next_indent)}
-#{other_element(false, next_indent)}
-#{indent}</item>
-EOT
-       		rv = @converter.convert(rv) if convert and @converter
+          rv = tag(indent) do |next_indent|
+            [
+              title_element(false, next_indent),
+              link_element(false, next_indent),
+              description_element(false, next_indent),
+              category_elements(false, next_indent),
+              source_element(false, next_indent),
+              enclosure_element(false, next_indent),
+              other_element(false, next_indent),
+            ]
+          end
+          rv = @converter.convert(rv) if convert and @converter
     	    rv
         end
 
         private
         def children
-          [@category, @source, @enclosure,].compact
+          [@source, @enclosure, *@category].compact
         end
 
         def _tags
-          %w(title link description author comments category
+          rv = %w(title link description author comments
             source enclosure).delete_if do |x|
             send(x).nil?
           end.collect do |x|
             [nil, x]
           end
+
+          @category.each do
+            rv << [nil, "category"]
+          end
+          
+          rv
+        end
+
+        def maker_target(maker)
+          maker.items.new_item
         end
 
+        def setup_maker_element(item)
+          super
+          @enclosure.setup_maker(item) if @enclosure
+          @source.setup_maker(item) if @source
+        end
+        
         class Source < Element
 
           include RSS09
@@ -364,17 +492,6 @@ EOT
             @content = content
           end
 
-          def to_s(convert=true, indent=calc_indent)
-            if @url
-              rv = %Q!				<source url="#{@url}">!
-              rv << %Q!#{@content}</source>!
-              rv = @converter.convert(rv) if convert and @converter
-              rv
-            else
-              ''
-            end
-          end
-
           private
           def _tags
             []
@@ -386,6 +503,15 @@ EOT
             ]
           end
 
+
+          def maker_target(item)
+            item.source
+          end
+
+          def setup_maker_attributes(source)
+            source.url = url
+            source.content = content
+          end
         end
 
         class Enclosure < Element
@@ -408,14 +534,9 @@ EOT
           end
 
           def to_s(convert=true, indent=calc_indent)
-            if @url and @length and @type
-              rv = %Q!<enclosure url="#{h @url}" !
-              rv << %Q!length="#{h @length}" type="#{h @type}"/>!
-              rv = @converter.convert(rv) if convert and @converter
-              rv
-            else
-              ''
-            end
+            rv = tag(indent)
+            rv = @converter.convert(rv) if convert and @converter
+            rv
           end
 
           private
@@ -427,6 +548,15 @@ EOT
             ]
           end
 
+          def maker_target(item)
+            item.enclosure
+          end
+
+          def setup_maker_attributes(enclosure)
+            enclosure.url = url
+            enclosure.length = length
+            enclosure.type = type
+          end
         end
 
         class Category < Element
@@ -447,17 +577,6 @@ EOT
             @content = content
           end
 
-          def to_s(convert=true, indent=calc_indent)
-            if @domain
-              rv = %Q!<category domain="#{h @domain}">!
-              rv << %Q!#{h @content}</category>!
-              rv = @converter.convert(rv) if convert and @converter
-              rv
-            else
-              ''
-            end
-          end
-
           private
           def _attrs
             [
@@ -465,12 +584,21 @@ EOT
             ]
           end
 
+          def maker_target(item)
+            item.new_category
+          end
+
+          def setup_maker_attributes(category)
+            category.domain = domain
+            category.content = content
+          end
+          
         end
 
       end
       
       class TextInput < Element
-        
+
         include RSS09
 
         %w(title description name link).each do |x|
@@ -479,16 +607,15 @@ EOT
         end
 
         def to_s(convert=true, indent=calc_indent)
-          next_indent = indent + INDENT
-          rv = <<-EOT
-#{indent}<textInput>
-#{title_element(false, next_indent)}
-#{description_element(false, next_indent)}
-#{name_element(false, next_indent)}
-#{link_element(false, next_indent)}
-#{other_element(false, next_indent)}
-#{indent}</textInput>
-EOT
+          rv = tag(indent) do |next_indent|
+            [
+              title_element(false, next_indent),
+              description_element(false, next_indent),
+              name_element(false, next_indent),
+              link_element(false, next_indent),
+              other_element(false, next_indent),
+            ]
+          end
        		rv = @converter.convert(rv) if convert and @converter
     	    rv
         end
@@ -501,6 +628,10 @@ EOT
             [nil, elem]
           end
         end
+
+        def maker_target(maker)
+          maker.textinput
+        end
       end
       
     end
diff --git a/lib/rss/1.0.rb b/lib/rss/1.0.rb
index 563ed66426..0e3e66ea95 100644
--- a/lib/rss/1.0.rb
+++ b/lib/rss/1.0.rb
@@ -18,7 +18,6 @@ module RSS
 
     include RSS10
     include RootElementMixin
-    include XMLStyleSheetMixin
 
     class << self
 
@@ -57,21 +56,22 @@ module RSS
       super('1.0', version, encoding, standalone)
     end
 
+    def full_name
+      tag_name_with_prefix(PREFIX)
+    end
+    
     def to_s(convert=true, indent=calc_indent)
-      next_indent = indent + INDENT
-      rv = <<-EORDF
-#{xmldecl}
-#{xml_stylesheet_pi}
-#{indent}<#{PREFIX}:RDF#{ns_declaration(next_indent)}>
-#{channel_element(false, next_indent)}
-#{image_element(false, next_indent)}
-#{item_elements(false, next_indent)}
-#{textinput_element(false, next_indent)}
-#{other_element(false, next_indent)}
-#{indent}</#{PREFIX}:RDF>
-EORDF
+      rv = tag(indent, ns_declarations) do |next_indent|
+        [
+          channel_element(false, next_indent),
+          image_element(false, next_indent),
+          item_elements(false, next_indent),
+          textinput_element(false, next_indent),
+          other_element(false, next_indent),
+        ]
+      end
       rv = @converter.convert(rv) if convert and @converter
-      remove_empty_newline(rv)
+      rv
     end
 
     private
@@ -119,16 +119,19 @@ EORDF
       end
       
       def to_s(convert=true, indent=calc_indent)
-        next_indent = indent + INDENT
-        <<-EOT
-#{indent}<#{PREFIX}:Seq>
-#{li_elements(convert, next_indent)}
-#{other_element(convert, next_indent)}
-#{indent}</#{PREFIX}:Seq>
-EOT
+        tag(indent) do |next_indent|
+          [
+            li_elements(convert, next_indent),
+            other_element(convert, next_indent),
+          ]
+        end
       end
 
-  		private
+      def full_name
+        tag_name_with_prefix(PREFIX)
+      end
+      
+      private
       def children
         @li
       end
@@ -169,15 +172,15 @@ EOT
         super()
         @resource = resource
       end
+
+      def full_name
+        tag_name_with_prefix(PREFIX)
+      end
       
       def to_s(convert=true, indent=calc_indent)
-        if @resource
-          rv = %Q!#{indent}<#{PREFIX}:li resource="#{h @resource}" />\n!
-          rv = @converter.convert(rv) if convert and @converter
-          rv
-        else
-          ''
-        end
+        rv = tag(indent)
+        rv = @converter.convert(rv) if convert and @converter
+        rv
       end
 
       private
@@ -232,20 +235,17 @@ EOT
       end
 
       def to_s(convert=true, indent=calc_indent)
-        next_indent = indent + INDENT
-        about = ''
-        about << %Q!#{PREFIX}:about="#{h @about}"! if @about
-        rv = <<-EOT
-#{indent}<channel #{about}>
-#{title_element(false, next_indent)}
-#{link_element(false, next_indent)}
-#{description_element(false, next_indent)}
-#{image_element(false, next_indent)}
-#{items_element(false, next_indent)}
-#{textinput_element(false, next_indent)}
-#{other_element(false, next_indent)}
-#{indent}</channel>
-EOT
+        rv = tag(indent) do |next_indent|
+          [
+            title_element(false, next_indent),
+            link_element(false, next_indent),
+            description_element(false, next_indent),
+            image_element(false, next_indent),
+            items_element(false, next_indent),
+            textinput_element(false, next_indent),
+            other_element(false, next_indent),
+          ]
+        end
         rv = @converter.convert(rv) if convert and @converter
   	    rv
       end
@@ -270,10 +270,18 @@ EOT
 
       def _attrs
         [
-          ["about", true]
+          ["#{PREFIX}:about", true, "about"]
         ]
       end
       
+      def maker_target(maker)
+        maker.channel
+      end
+      
+      def setup_maker_attributes(channel)
+        channel.about = self.about
+      end
+
       class Image < Element
         
         include RSS10
@@ -298,22 +306,17 @@ EOT
         end
 
         def to_s(convert=true, indent=calc_indent)
-          if @resource
-            rv = %Q!#{indent}<image #{PREFIX}:resource="#{h @resource}" />!
-            rv = @converter.convert(rv) if convert and @converter
-            rv
-          else
-            ''
-          end
+          rv = tag(indent)
+          rv = @converter.convert(rv) if convert and @converter
+          rv
         end
 
         private
         def _attrs
           [
-            ["resource", true]
+            ["#{PREFIX}:resource", true, "resource"]
           ]
         end
-
       end
 
       class Textinput < Element
@@ -340,22 +343,17 @@ EOT
         end
 
         def to_s(convert=true, indent=calc_indent)
-          if @resource
-            rv = %Q|#{indent}<textinput #{PREFIX}:resource="#{h @resource}" />|
-            rv = @converter.convert(rv) if convert and @converter
-            rv
-          else
-            ''
-          end
+          rv = tag(indent)
+          rv = @converter.convert(rv) if convert and @converter
+          rv
         end
         
         private
         def _attrs
           [
-            ["resource", true],
+            ["#{PREFIX}:resource", true, "resource"]
           ]
         end
-
       end
       
       class Items < Element
@@ -387,13 +385,12 @@ EOT
         end
         
         def to_s(convert=true, indent=calc_indent)
-          next_indent = indent + INDENT
-          <<-EOT
-#{indent}<items>
-#{Seq_element(convert, next_indent)}
-#{other_element(convert, next_indent)}
-#{indent}</items>
-EOT
+          rv = tag(indent) do |next_indent|
+            [
+              Seq_element(convert, next_indent),
+              other_element(convert, next_indent),
+            ]
+          end
         end
 
         private
@@ -452,17 +449,14 @@ EOT
       end
 
       def to_s(convert=true, indent=calc_indent)
-        next_indent = indent + INDENT
-        about = ''
-        about << %Q!#{PREFIX}:about="#{h @about}"! if @about
-        rv = <<-EOT
-#{indent}<image #{about}>
-#{title_element(false, next_indent)}
-#{url_element(false, next_indent)}
-#{link_element(false, next_indent)}
-#{other_element(false, next_indent)}
-#{indent}</image>
-EOT
+        rv = tag(indent) do |next_indent|
+          [
+            title_element(false, next_indent),
+            url_element(false, next_indent),
+            link_element(false, next_indent),
+            other_element(false, next_indent),
+          ]
+        end
         rv = @converter.convert(rv) if convert and @converter
         rv
       end
@@ -480,10 +474,13 @@ EOT
 
       def _attrs
         [
-          ["about", true],
+          ["#{PREFIX}:about", true, "about"]
         ]
       end
 
+      def maker_target(maker)
+        maker.image
+      end
     end
 
     class Item < Element
@@ -522,17 +519,14 @@ EOT
       end
 
       def to_s(convert=true, indent=calc_indent)
-        next_indent = indent + INDENT
-        about = ''
-        about << %Q!#{PREFIX}:about="#{h @about}"! if @about
-        rv = <<-EOT
-#{indent}<item #{about}>
-#{title_element(false, next_indent)}
-#{link_element(false, next_indent)}
-#{description_element(false, next_indent)}
-#{other_element(false, next_indent)}
-#{indent}</item>
-EOT
+        rv = tag(indent) do |next_indent|
+          [
+            title_element(false, next_indent),
+            link_element(false, next_indent),
+            description_element(false, next_indent),
+            other_element(false, next_indent),
+          ]
+        end
         rv = @converter.convert(rv) if convert and @converter
         rv
       end
@@ -550,10 +544,13 @@ EOT
 
       def _attrs
         [
-          ["about", true],
+          ["#{PREFIX}:about", true, "about"]
         ]
       end
 
+      def maker_target(maker)
+        maker.items.new_item
+      end
     end
 
     class Textinput < Element
@@ -593,18 +590,15 @@ EOT
       end
 
       def to_s(convert=true, indent=calc_indent)
-        next_indent = indent + INDENT
-        about = ''
-        about << %Q!#{PREFIX}:about="#{h @about}"! if @about
-        rv = <<-EOT
-#{indent}<textinput #{about}>
-#{title_element(false, next_indent)}
-#{description_element(false, next_indent)}
-#{name_element(false, next_indent)}
-#{link_element(false, next_indent)}
-#{other_element(false, next_indent)}
-#{indent}</textinput>
-EOT
+        rv = tag(indent) do |next_indent|
+          [
+            title_element(false, next_indent),
+            description_element(false, next_indent),
+            name_element(false, next_indent),
+            link_element(false, next_indent),
+            other_element(false, next_indent),
+          ]
+        end
         rv = @converter.convert(rv) if convert and @converter
         rv
       end
@@ -623,10 +617,13 @@ EOT
       
       def _attrs
         [
-          ["about", true],
+          ["#{PREFIX}:about", true, "about"]
         ]
       end
 
+      def maker_target(maker)
+        maker.textinput
+      end
     end
 
   end
diff --git a/lib/rss/2.0.rb b/lib/rss/2.0.rb
index 7fafb23ba9..19cb487d79 100644
--- a/lib/rss/2.0.rb
+++ b/lib/rss/2.0.rb
@@ -11,11 +11,18 @@ module RSS
         install_model(x, '?')
       end
 
-      %w(category).each do |x|
-        install_have_child_element(x)
-        install_model(x, '?')
+      remove_method :ttl=
+      def ttl=(value)
+        @ttl = value.to_i
       end
-
+      
+      [
+        %w(category categories),
+      ].each do |name, plural_name|
+        install_have_children_element(name, plural_name)
+        install_model(name, '*')
+      end
+        
       [
         ["image", "?"],
         ["language", "?"],
@@ -25,7 +32,7 @@ module RSS
 
       def other_element(convert, indent)
         rv = <<-EOT
-#{category_element(convert, indent)}
+#{category_elements(convert, indent)}
 #{generator_element(convert, indent)}
 #{ttl_element(convert, indent)}
 EOT
@@ -35,16 +42,22 @@ EOT
       private
       alias children09 children
       def children
-        children09 + [@category].compact
+        children09 + @category.compact
       end
 
       alias _tags09 _tags
       def _tags
-        %w(generator ttl category).delete_if do |x|
+        rv = %w(generator ttl).delete_if do |x|
           send(x).nil?
         end.collect do |elem|
           [nil, elem]
         end + _tags09
+
+        @category.each do
+          rv << [nil, "category"]
+        end
+        
+        rv
       end
 
       Category = Item::Category
@@ -74,13 +87,15 @@ EOT
         end
       
         def other_element(convert, indent)
-          rv = <<-EOT
-#{author_element(false, indent)}
-#{comments_element(false, indent)}
-#{pubDate_element(false, indent)}
-#{guid_element(false, indent)}
-EOT
-          rv << super
+          rv = [
+            super,
+            *%w(author comments pubDate guid).collect do |name|
+              __send__("#{name}_element", false, indent)
+            end
+          ].reject do |value|
+            /\A\s*\z/.match(value)
+          end
+          rv.join("\n")
         end
 
         private
@@ -98,6 +113,12 @@ EOT
           end + _tags09
         end
 
+        alias _setup_maker_element setup_maker_element
+        def setup_maker_element(item)
+          _setup_maker_element(item)
+          @guid.setup_maker(item) if @guid
+        end
+        
         class Guid < Element
           
           include RSS09
@@ -116,18 +137,6 @@ EOT
             @content = content
           end
 
-          def to_s(convert=true, indent=calc_indent)
-            if @content
-              rv = %Q!<guid!
-              rv << %Q! isPermaLink="#{h @isPermaLink}"! if @isPermaLink
-              rv << %Q!>#{h @content}</guid>!
-              rv = @converter.convert(rv) if convert and @converter
-              rv
-            else
-              ''
-            end
-          end
-
           private
           def _attrs
             [
@@ -135,6 +144,14 @@ EOT
             ]
           end
 
+          def maker_target(item)
+            item.guid
+          end
+
+          def setup_maker_attributes(guid)
+            guid.isPermaLink = isPermaLink
+            guid.content = content
+          end
         end
 
       end
diff --git a/lib/rss/maker.rb b/lib/rss/maker.rb
index c158c726c3..66c3bc2928 100644
--- a/lib/rss/maker.rb
+++ b/lib/rss/maker.rb
@@ -7,12 +7,7 @@ module RSS
     MAKERS = {}
     
     class << self
-      def make(version, modules=[], &block)
-        prefix = "rss/maker"
-        require "#{prefix}/#{version}"
-        modules.each do |mod|
-          require "#{prefix}/#{mod}"
-        end
+      def make(version, &block)
         maker(version).make(&block)
       end
 
@@ -31,3 +26,10 @@ module RSS
   end
   
 end
+
+require "rss/maker/1.0"
+require "rss/maker/2.0"
+require "rss/maker/content"
+require "rss/maker/dublincore"
+require "rss/maker/syndication"
+require "rss/maker/trackback"
diff --git a/lib/rss/maker/0.9.rb b/lib/rss/maker/0.9.rb
index 05578082b0..b82585fb96 100644
--- a/lib/rss/maker/0.9.rb
+++ b/lib/rss/maker/0.9.rb
@@ -11,23 +11,15 @@ module RSS
         super
       end
       
-      def to_rss
-        rss = Rss.new(@rss_version, @version, @encoding, @standalone)
-        setup_xml_stylesheets(rss)
-        setup_channel(rss)
-        setup_other_elements(rss)
-        if rss.channel
-          rss
-        else
-          nil
-        end
-      end
-      
       private
-      def setup_channel(rss)
-        @channel.to_rss(rss)
+      def make_rss
+        Rss.new(@rss_version, @version, @encoding, @standalone)
       end
-      
+
+      def setup_elements(rss)
+        setup_channel(rss)
+      end
+
       class Channel < ChannelBase
         
         def to_rss(rss)
@@ -44,12 +36,13 @@ module RSS
             else
               nil
             end
+          elsif variable_is_set?
+            raise NotSetError.new("maker.channel", not_set_required_variables)
           end
         end
         
         def have_required_values?
-          @title and @link and @description and @language and
-            @maker.image.have_required_values?
+          @title and @link and @description and @language
         end
         
         private
@@ -69,9 +62,76 @@ module RSS
           super + ["pubDate"]
         end
 
+        def required_variable_names
+          %w(title link description language)
+        end
+        
+        class SkipDays < SkipDaysBase
+          def to_rss(rss, channel)
+            unless @days.empty?
+              skipDays = Rss::Channel::SkipDays.new
+              channel.skipDays = skipDays
+              @days.each do |day|
+                day.to_rss(rss, skipDays.days)
+              end
+            end
+          end
+          
+          class Day < DayBase
+            def to_rss(rss, days)
+              day = Rss::Channel::SkipDays::Day.new
+              set = setup_values(day)
+              if set
+                days << day
+                setup_other_elements(rss)
+              end
+            end
+
+            def have_required_values?
+              @content
+            end
+          end
+        end
+        
+        class SkipHours < SkipHoursBase
+          def to_rss(rss, channel)
+            unless @hours.empty?
+              skipHours = Rss::Channel::SkipHours.new
+              channel.skipHours = skipHours
+              @hours.each do |hour|
+                hour.to_rss(rss, skipHours.hours)
+              end
+            end
+          end
+          
+          class Hour < HourBase
+            def to_rss(rss, hours)
+              hour = Rss::Channel::SkipHours::Hour.new
+              set = setup_values(hour)
+              if set
+                hours << hour
+                setup_other_elements(rss)
+              end
+            end
+
+            def have_required_values?
+              @content
+            end
+          end
+        end
+        
         class Cloud < CloudBase
+          def to_rss(*args)
+          end
         end
 
+        class Categories < CategoriesBase
+          def to_rss(*args)
+          end
+
+          class Category < CategoryBase
+          end
+        end
       end
       
       class Image < ImageBase
@@ -130,9 +190,12 @@ module RSS
             end
           end
         
-          class Category < CategoryBase
+          class Categories < CategoriesBase
             def to_rss(*args)
             end
+
+            class Category < CategoryBase
+            end
           end
           
         end
@@ -156,5 +219,6 @@ module RSS
     end
     
     add_maker(filename_to_version(__FILE__), RSS09)
+    add_maker(filename_to_version(__FILE__) + "1", RSS09)
   end
 end
diff --git a/lib/rss/maker/1.0.rb b/lib/rss/maker/1.0.rb
index 894bcc0a24..e38a2f89e0 100644
--- a/lib/rss/maker/1.0.rb
+++ b/lib/rss/maker/1.0.rb
@@ -11,41 +11,22 @@ module RSS
         super("1.0")
       end
 
-      def to_rss
-        rss = RDF.new(@version, @encoding, @standalone)
-        setup_xml_stylesheets(rss)
+      private
+      def make_rss
+        RDF.new(@version, @encoding, @standalone)
+      end
+
+      def setup_elements(rss)
         setup_channel(rss)
         setup_image(rss)
         setup_items(rss)
         setup_textinput(rss)
-        setup_other_elements(rss)
-        if rss.channel
-          rss
-        else
-          nil
-        end
-      end
-
-      private
-      def setup_channel(rss)
-        @channel.to_rss(rss)
-      end
-
-      def setup_image(rss)
-        @image.to_rss(rss)
-      end
-
-      def setup_items(rss)
-        @items.to_rss(rss)
-      end
-
-      def setup_textinput(rss)
-        @textinput.to_rss(rss)
       end
 
       class Channel < ChannelBase
 
         def to_rss(rss)
+          set = false
           if @about
             channel = RDF::Channel.new(@about)
             set = setup_values(channel)
@@ -57,12 +38,16 @@ module RSS
               setup_other_elements(rss)
             end
           end
+
+          if (!@about or !set) and variable_is_set?
+            raise NotSetError.new("maker.channel", not_set_required_variables)
+          end
         end
 
         def have_required_values?
           @about and @title and @link and @description
         end
-        
+
         private
         def setup_items(rss)
           items = RDF::Channel::Items.new
@@ -86,7 +71,37 @@ module RSS
           end
         end
 
+        def required_variable_names
+          %w(about title link description)
+        end
+        
+        class SkipDays < SkipDaysBase
+          def to_rss(*args)
+          end
+          
+          class Day < DayBase
+          end
+        end
+        
+        class SkipHours < SkipHoursBase
+          def to_rss(*args)
+          end
+
+          class Hour < HourBase
+          end
+        end
+        
         class Cloud < CloudBase
+          def to_rss(*args)
+          end
+        end
+
+        class Categories < CategoriesBase
+          def to_rss(*args)
+          end
+
+          class Category < CategoryBase
+          end
         end
       end
 
@@ -153,9 +168,12 @@ module RSS
             end
           end
         
-          class Category < CategoryBase
+          class Categories < CategoriesBase
             def to_rss(*args)
             end
+
+            class Category < CategoryBase
+            end
           end
         end
       end
diff --git a/lib/rss/maker/2.0.rb b/lib/rss/maker/2.0.rb
index 05fc46480a..a958661614 100644
--- a/lib/rss/maker/2.0.rb
+++ b/lib/rss/maker/2.0.rb
@@ -13,23 +13,30 @@ module RSS
 
       class Channel < RSS09::Channel
 
-        add_other_element("cloud")
-        
         def have_required_values?
           @title and @link and @description
         end
 
-        private
-        def setup_cloud(rss, current)
-          @maker.channel.cloud.to_rss(rss)
+        def required_variable_names
+          %w(title link description)
         end
-
+        
+        class SkipDays < RSS09::Channel::SkipDays
+          class Day < RSS09::Channel::SkipDays::Day
+          end
+        end
+        
+        class SkipHours < RSS09::Channel::SkipHours
+          class Hour < RSS09::Channel::SkipHours::Hour
+          end
+        end
+        
         class Cloud < RSS09::Channel::Cloud
-          def to_rss(rss)
+          def to_rss(rss, channel)
             cloud = Rss::Channel::Cloud.new
             set = setup_values(cloud)
             if set
-              rss.channel.cloud = cloud
+              channel.cloud = cloud
               setup_other_elements(rss)
             end
           end
@@ -39,6 +46,30 @@ module RSS
               @registerProcedure and @protocol
           end
         end
+
+        class Categories < RSS09::Channel::Categories
+          def to_rss(rss, channel)
+            @categories.each do |category|
+              category.to_rss(rss, channel)
+            end
+          end
+          
+          class Category < RSS09::Channel::Categories::Category
+            def to_rss(rss, channel)
+              category = Rss::Channel::Category.new
+              set = setup_values(category)
+              if set
+                channel.categories << category
+                setup_other_elements(rss)
+              end
+            end
+            
+            def have_required_values?
+              @content
+            end
+          end
+        end
+        
       end
       
       class Image < RSS09::Image
@@ -102,18 +133,26 @@ module RSS
             end
           end
 
-          class Category < RSS09::Items::Item::Category
+          class Categories < RSS09::Items::Item::Categories
             def to_rss(rss, item)
-              category = Rss::Channel::Item::Category.new
-              set = setup_values(category)
-              if set
-                item.category = category
-                setup_other_elements(rss)
+              @categories.each do |category|
+                category.to_rss(rss, item)
               end
             end
-            
-            def have_required_values?
-              @content
+          
+            class Category < RSS09::Items::Item::Categories::Category
+              def to_rss(rss, item)
+                category = Rss::Channel::Item::Category.new
+                set = setup_values(category)
+                if set
+                  item.categories << category
+                  setup_other_elements(rss)
+                end
+              end
+              
+              def have_required_values?
+                @content
+              end
             end
           end
         end
diff --git a/lib/rss/maker/base.rb b/lib/rss/maker/base.rb
index 21222351f2..93f668beff 100644
--- a/lib/rss/maker/base.rb
+++ b/lib/rss/maker/base.rb
@@ -38,13 +38,24 @@ module RSS
           OTHER_ELEMENTS
         end
 
-        def self.add_need_initialize_variable(variable_name)
-          const_get("NEED_INITIALIZE_VARIABLES") << variable_name
+        def self.add_need_initialize_variable(variable_name, init_value="nil")
+          const_get("NEED_INITIALIZE_VARIABLES") << [variable_name, init_value]
         end
 
         def self.need_initialize_variables
           NEED_INITIALIZE_VARIABLES
         end
+
+        def self.def_array_element(name)
+          include Enumerable
+          extend Forwardable
+
+          def_delegators("@\#{name}", :<<, :[], :[]=, :first, :last)
+          def_delegators("@\#{name}", :push, :pop, :shift, :unshift)
+          def_delegators("@\#{name}", :each)
+          
+          add_need_initialize_variable(name, "[]")
+        end
         EOC
       end
       
@@ -59,8 +70,8 @@ module RSS
       
       private
       def initialize_variables
-        self.class.need_initialize_variables.each do |variable_name|
-          instance_eval("@#{variable_name} = nil", __FILE__, __LINE__)
+        self.class.need_initialize_variables.each do |variable_name, init_value|
+          instance_eval("@#{variable_name} = #{init_value}", __FILE__, __LINE__)
         end
       end
 
@@ -88,7 +99,28 @@ module RSS
       end
 
       def variables
-        self.class.need_initialize_variables
+        self.class.need_initialize_variables.find_all do |name, init|
+          "nil" == init
+        end.collect do |name, init|
+          name
+        end
+      end
+
+      def variable_is_set?
+        variables.find {|var| !__send__(var).nil?}
+      end
+
+      def not_set_required_variables
+        required_variable_names.find_all do |var|
+          __send__(var).nil?
+        end
+      end
+
+      def required_variables_are_set?
+        required_variable_names.each do |var|
+          return false if __send__(var).nil?
+        end
+        true
       end
       
     end
@@ -102,9 +134,22 @@ module RSS
         end
       end
 
-      attr_reader :rss_version, :xml_stylesheets
-      attr_reader :channel, :image, :items, :textinput
+      %w(xml_stylesheets channel image items textinput).each do |element|
+        attr_reader element
+        add_need_initialize_variable(element, "make_#{element}")
+        module_eval(<<-EOC, __FILE__, __LINE__)
+          private
+          def setup_#{element}(rss)
+            @#{element}.to_rss(rss)
+          end
+
+          def make_#{element}
+            self.class::#{element[0,1].upcase}#{element[1..-1]}.new(self)
+          end
+EOC
+      end
       
+      attr_reader :rss_version
       attr_accessor :version, :encoding, :standalone
       
       def initialize(rss_version)
@@ -113,63 +158,45 @@ module RSS
         @version = "1.0"
         @encoding = "UTF-8"
         @standalone = nil
-        @xml_stylesheets = make_xml_stylesheets
-        @channel = make_channel
-        @image = make_image
-        @items = make_items
-        @textinput = make_textinput
       end
       
-      def make(&block)
-        block.call(self) if block
-        to_rss
+      def make
+        if block_given?
+          yield(self)
+          to_rss
+        else
+          nil
+        end
       end
 
+      def to_rss
+        rss = make_rss
+        setup_xml_stylesheets(rss)
+        setup_elements(rss)
+        setup_other_elements(rss)
+        if rss.channel
+          rss
+        else
+          nil
+        end
+      end
+      
       def current_element(rss)
         rss
       end
       
       private
+      remove_method :make_xml_stylesheets
       def make_xml_stylesheets
         XMLStyleSheets.new(self)
       end
       
-      def make_channel
-        self.class::Channel.new(self)
-      end
-      
-      def make_image
-        self.class::Image.new(self)
-      end
-      
-      def make_items
-        self.class::Items.new(self)
-      end
-      
-      def make_textinput
-        self.class::Textinput.new(self)
-      end
-
-      def setup_xml_stylesheets(rss)
-        @xml_stylesheets.to_rss(rss)
-      end
-      
     end
 
     class XMLStyleSheets
       include Base
 
-      include Enumerable
-      extend Forwardable
-
-      def_delegators(:@xml_stylesheets, :<<, :[], :[]=, :first, :last)
-      def_delegators(:@xml_stylesheets, :push, :pop, :shift, :unshift)
-      def_delegators(:@xml_stylesheets, :each)
-
-      def initialize(maker)
-        super
-        @xml_stylesheets = []
-      end
+      def_array_element("xml_stylesheets")
 
       def to_rss(rss)
         @xml_stylesheets.each do |xss|
@@ -217,12 +244,25 @@ module RSS
     class ChannelBase
       include Base
 
-      attr_reader :cloud
+      %w(cloud categories skipDays skipHours).each do |element|
+        attr_reader element
+        add_other_element(element)
+        add_need_initialize_variable(element, "make_#{element}")
+        module_eval(<<-EOC, __FILE__, __LINE__)
+          private
+          def setup_#{element}(rss, current)
+            @#{element}.to_rss(rss, current)
+          end
+
+          def make_#{element}
+            self.class::#{element[0,1].upcase}#{element[1..-1]}.new(@maker)
+          end
+EOC
+      end
 
       %w(about title link description language copyright
-      managingEditor webMaster rating docs skipDays
-      skipHours date lastBuildDate category generator ttl
-      ).each do |element|
+         managingEditor webMaster rating docs date
+         lastBuildDate generator ttl).each do |element|
         attr_accessor element
         add_need_initialize_variable(element)
       end
@@ -230,18 +270,68 @@ module RSS
       alias_method(:pubDate, :date)
       alias_method(:pubDate=, :date=)
 
-      def initialize(maker)
-        super
-        @cloud = make_cloud
-      end
-
       def current_element(rss)
         rss.channel
       end
 
-      private
-      def make_cloud
-        self.class::Cloud.new(@maker)
+      class SkipDaysBase
+        include Base
+
+        def_array_element("days")
+
+        def new_day
+          day = self.class::Day.new(@maker)
+          @days << day 
+          day
+        end
+        
+        def current_element(rss)
+          rss.channel.skipDays
+        end
+
+        class DayBase
+          include Base
+          
+          %w(content).each do |element|
+            attr_accessor element
+            add_need_initialize_variable(element)
+          end
+
+          def current_element(rss)
+            rss.channel.skipDays.last
+          end
+
+        end
+      end
+      
+      class SkipHoursBase
+        include Base
+
+        def_array_element("hours")
+
+        def new_hour
+          hour = self.class::Hour.new(@maker)
+          @hours << hour 
+          hour
+        end
+        
+        def current_element(rss)
+          rss.channel.skipHours
+        end
+
+        class HourBase
+          include Base
+          
+          %w(content).each do |element|
+            attr_accessor element
+            add_need_initialize_variable(element)
+          end
+
+          def current_element(rss)
+            rss.channel.skipHours.last
+          end
+
+        end
       end
       
       class CloudBase
@@ -257,6 +347,27 @@ module RSS
         end
 
       end
+
+      class CategoriesBase
+        include Base
+        
+        def_array_element("categories")
+
+        def new_category
+          category = self.class::Category.new(@maker)
+          @categories << category
+          category
+        end
+
+        class CategoryBase
+          include Base
+
+          %w(domain content).each do |element|
+            attr_accessor element
+            add_need_initialize_variable(element)
+          end
+        end
+      end
     end
     
     class ImageBase
@@ -279,23 +390,18 @@ module RSS
     class ItemsBase
       include Base
 
-      include Enumerable
-      extend Forwardable
-
-      def_delegators(:@items, :<<, :[], :[]=, :first, :last)
-      def_delegators(:@items, :push, :pop, :shift, :unshift)
-      def_delegators(:@items, :each)
+      def_array_element("items")
       
-      attr_accessor :do_sort
+      attr_accessor :do_sort, :max_size
       
       def initialize(maker)
         super
-        @items = []
         @do_sort = false
+        @max_size = -1
       end
       
       def normalize
-        sort_if_need
+        sort_if_need[0..@max_size]
       end
       
       def current_element(rss)
@@ -326,9 +432,10 @@ module RSS
       class ItemBase
         include Base
         
-        %w(guid enclosure source category).each do |element|
+        %w(guid enclosure source categories).each do |element|
           attr_reader element
           add_other_element(element)
+          add_need_initialize_variable(element, "make_#{element}")
           module_eval(<<-EOC, __FILE__, __LINE__)
           private
           def setup_#{element}(rss, current)
@@ -349,14 +456,6 @@ EOC
         alias_method(:pubDate, :date)
         alias_method(:pubDate=, :date=)
 
-        def initialize(maker)
-          super
-          @guid = make_guid
-          @enclosure = make_enclosure
-          @source = make_source
-          @category = make_category
-        end
-      
         def <=>(other)
           if @date and other.date
             @date <=> other.date
@@ -400,14 +499,7 @@ EOC
           end
         end
       
-        class CategoryBase
-          include Base
-
-          %w(domain content).each do |element|
-            attr_accessor element
-            add_need_initialize_variable(element)
-          end
-        end
+        CategoriesBase = ChannelBase::CategoriesBase
       
       end
     end
diff --git a/lib/rss/maker/trackback.rb b/lib/rss/maker/trackback.rb
index 1ec59ab0b0..ef78bf2f20 100644
--- a/lib/rss/maker/trackback.rb
+++ b/lib/rss/maker/trackback.rb
@@ -1,5 +1,6 @@
 require 'rss/trackback'
 require 'rss/maker/1.0'
+require 'rss/maker/2.0'
 
 module RSS
   module Maker
@@ -7,18 +8,65 @@ module RSS
       def self.append_features(klass)
         super
 
-        %w(ping about).each do |element|
-          name = "#{RSS::TRACKBACK_PREFIX}_#{element}"
-          klass.add_need_initialize_variable(name)
-          klass.add_other_element(name)
-          klass.__send__(:attr_accessor, name)
-          klass.module_eval(<<-EOC, __FILE__, __LINE__)
-            def setup_#{name}(rss, current)
-              if #{name} and current.respond_to?(:#{name}=)
-                current.#{name} = @#{name} if @#{name}
-              end
+        name = "#{RSS::TRACKBACK_PREFIX}_ping"
+        klass.add_need_initialize_variable(name)
+        klass.add_other_element(name)
+        klass.__send__(:attr_accessor, name)
+        klass.module_eval(<<-EOC, __FILE__, __LINE__)
+          def setup_#{name}(rss, current)
+            if #{name} and current.respond_to?(:#{name}=)
+              current.#{name} = #{name}
             end
-          EOC
+          end
+        EOC
+
+        name = "#{RSS::TRACKBACK_PREFIX}_abouts"
+        klass.add_need_initialize_variable(name, "make_#{name}")
+        klass.add_other_element(name)
+        klass.__send__(:attr_accessor, name)
+        klass.module_eval(<<-EOC, __FILE__, __LINE__)
+          def make_#{name}
+            self.class::TrackBackAbouts.new(self)
+          end
+
+          def setup_#{name}(rss, current)
+            @#{name}.to_rss(rss, current)
+          end
+        EOC
+      end
+
+      class TrackBackAboutsBase
+        include Base
+
+        def_array_element("abouts")
+        
+        def new_about
+          about = self.class::About.new(@maker)
+          @abouts << about 
+          about
+        end
+
+        def to_rss(rss, current)
+          @abouts.each do |about|
+            about.to_rss(rss, current)
+          end
+        end
+        
+        class AboutBase
+          include Base
+
+          attr_accessor :value
+          add_need_initialize_variable(:value)
+          
+          alias_method(:resource, :value)
+          alias_method(:resource=, :value=)
+          alias_method(:content, :value)
+          alias_method(:content=, :value=)
+        
+          def have_required_values?
+            @value
+          end
+          
         end
       end
     end
@@ -26,5 +74,53 @@ module RSS
     class ItemsBase
       class ItemBase; include TrackBackModel; end
     end
+
+    class RSS10
+      class Items
+        class Item
+          class TrackBackAbouts < TrackBackAboutsBase
+            class About < AboutBase
+              def to_rss(rss, current)
+                if resource
+                  about = ::RSS::TrackBackModel10::About.new(resource)
+                  current.trackback_abouts << about
+                end
+              end
+            end
+          end
+        end
+      end
+    end
+
+    class RSS09
+      class Items
+        class Item
+          class TrackBackAbouts < TrackBackAboutsBase
+            def to_rss(*args)
+            end
+            class About < AboutBase
+            end
+          end
+        end
+      end
+    end
+    
+    class RSS20
+      class Items
+        class Item
+          class TrackBackAbouts < TrackBackAboutsBase
+            class About < AboutBase
+              def to_rss(rss, current)
+                if content
+                  about = ::RSS::TrackBackModel20::About.new(content)
+                  current.trackback_abouts << about
+                end
+              end
+            end
+          end
+        end
+      end
+    end
+    
   end
 end
diff --git a/lib/rss/parser.rb b/lib/rss/parser.rb
index 09b3213372..1030c8f5d4 100644
--- a/lib/rss/parser.rb
+++ b/lib/rss/parser.rb
@@ -348,6 +348,13 @@ module RSS
         end
 
         if @do_validate and required and val.nil?
+          unless a_uri.include?(nil)
+            for prefix, uri in ns
+              if a_uri.include?(uri)
+                a_name = "#{prefix}:#{a_name}"
+              end
+            end
+          end
           raise MissingAttributeError.new(tag_name, a_name)
         end
 
@@ -357,10 +364,9 @@ module RSS
       previous = @last_element
       next_element = klass.send(:new, *args)
       next_element.do_validate = @do_validate
-      setter = ""
-      setter << "#{klass.required_prefix}_" if klass.required_prefix
-      setter << "#{tag_name}="
-      @last_element.send(setter, next_element)
+      prefix = ""
+      prefix << "#{klass.required_prefix}_" if klass.required_prefix
+      previous.__send__(:set_next_element, prefix, tag_name, next_element)
       @last_element = next_element
       @proc_stack.push Proc.new { |text, tags|
         p(@last_element.class) if DEBUG
diff --git a/lib/rss/rexmlparser.rb b/lib/rss/rexmlparser.rb
index 375b7794fb..73e352a731 100644
--- a/lib/rss/rexmlparser.rb
+++ b/lib/rss/rexmlparser.rb
@@ -36,7 +36,7 @@ module RSS
     include ListenerMixin
 
     def xmldecl(version, encoding, standalone)
-      super
+      super(version, encoding, standalone == "yes")
       # Encoding is converted to UTF-8 when REXML parse XML.
       @encoding = 'UTF-8'
     end
diff --git a/lib/rss/rss.rb b/lib/rss/rss.rb
index b6afa24b93..11fe6d6dd1 100644
--- a/lib/rss/rss.rb
+++ b/lib/rss/rss.rb
@@ -58,7 +58,7 @@ require "rss/xml-stylesheet"
 
 module RSS
 
-  VERSION = "0.1.0"
+  VERSION = "0.1.2"
 
   URI = "http://purl.org/rss/1.0/"
 
@@ -144,6 +144,15 @@ module RSS
     end
   end
 
+  class NotSetError < Error
+    attr_reader :name, :variables
+    def initialize(name, variables)
+      @name = name
+      @variables = variables
+      super("required variables of #{@name} are not set: #{@variables.join(', ')}")
+    end
+  end
+  
   module BaseModel
 
     include Utils
@@ -164,17 +173,20 @@ EOC
     end
     alias_method(:install_have_attribute_element, :install_have_child_element)
 
-    def install_have_children_element(name, postfix="s")
-      add_have_children_element(name)
-
-      def_children_accessor(name, postfix)
-      install_element(name, postfix) do |n, elem_name|
+    def install_have_children_element(name, plural_name=nil)
+      plural_name ||= "#{name}s"
+      add_have_children_element(name, plural_name)
+      add_plural_form(name, plural_name)
+      
+      def_children_accessor(name, plural_name)
+      install_element(name, "s") do |n, elem_name|
         <<-EOC
-        rv = ''
+        rv = []
         @#{n}.each do |x|
-          rv << "\#{x.to_s(convert, indent)}"
+          value = "\#{x.to_s(convert, indent)}"
+          rv << value if /\\A\\s*\\z/ !~ value
         end
-        rv
+        rv.join("\n")
 EOC
       end
     end
@@ -289,9 +301,9 @@ EOC
       end
     end
 
-    def def_children_accessor(accessor_name, postfix="s")
+    def def_children_accessor(accessor_name, plural_name)
       module_eval(<<-EOC, *get_file_and_line_from_caller(2))
-      def #{accessor_name}#{postfix}
+      def #{plural_name}
         @#{accessor_name}
       end
 
@@ -302,8 +314,12 @@ EOC
           @#{accessor_name}.send("[]", *args)
         end
       end
-        
+
       def #{accessor_name}=(*args)
+        warn("Warning:\#{caller.first.sub(/:in `.*'\z/, '')}: " \
+             "Don't use `#{accessor_name} = XXX'/`set_#{accessor_name}(XXX)'. " \
+             "Those APIs are not sense of Ruby. " \
+             "Use `#{plural_name} << XXX' instead of them.")
         if args.size == 1
           @#{accessor_name}.push(args[0])
         else
@@ -314,6 +330,22 @@ EOC
 EOC
     end
 
+    def def_content_only_to_s
+      module_eval(<<-EOC, *get_file_and_line_from_caller(2))
+      def to_s(convert=true, indent=calc_indent)
+        if @content
+          rv = tag(indent) do |next_indent|
+            h(@content)
+          end
+          rv = @converter.convert(rv) if convert and @converter
+          rv
+        else
+          ""
+        end
+      end
+EOC
+    end
+    
   end
 
   class Element
@@ -329,7 +361,8 @@ EOC
         klass.module_eval(<<-EOC)
         public
         
-        @tag_name = name.split(/::/).last.downcase
+        @tag_name = name.split(/::/).last
+        @tag_name[0,1] = @tag_name[0,1].downcase
         @indent_size = name.split(/::/).size - 2
 
         @@must_call_validators = {}
@@ -373,6 +406,7 @@ EOC
         def self.content_setup
           attr_writer :content
           convert_attr_reader :content
+          def_content_only_to_s
           @@have_content = true
         end
 
@@ -386,8 +420,8 @@ EOC
           @@have_children_elements
         end
 
-        def self.add_have_children_element(variable_name)
-          @@have_children_elements << variable_name
+        def self.add_have_children_element(variable_name, plural_name)
+          @@have_children_elements << [variable_name, plural_name]
         end
         
         @@need_initialize_variables = []
@@ -400,6 +434,16 @@ EOC
           @@need_initialize_variables
         end
 
+        @@plural_forms = {}
+        
+        def self.add_plural_form(singular, plural)
+          @@plural_forms[singular] = plural
+        end
+        
+        def self.plural_forms
+          @@plural_forms
+        end
+        
         EOC
       end
 
@@ -440,6 +484,14 @@ EOC
       self.class.tag_name
     end
 
+    def full_name
+      tag_name
+    end
+    
+    def indent_size
+      self.class.indent_size
+    end
+    
     def converter=(converter)
       @converter = converter
       children.each do |child|
@@ -457,6 +509,15 @@ EOC
       __validate(tags, false)
     end
 
+    def setup_maker(maker)
+      target = maker_target(maker)
+      unless target.nil?
+        setup_maker_attributes(target)
+        setup_maker_element(target)
+        setup_maker_elements(target)
+      end
+    end
+    
     private
     def initialize_variables
       self.class.need_initialize_variables.each do |variable_name|
@@ -467,11 +528,111 @@ EOC
     end
 
     def initialize_have_children_elements
-      self.class.have_children_elements.each do |variable_name|
+      self.class.have_children_elements.each do |variable_name, plural_name|
         instance_eval("@#{variable_name} = []")
       end
     end
 
+    def tag(indent, additional_attrs=[], &block)
+      next_indent = indent + INDENT
+
+      attrs = collect_attrs
+      return "" if attrs.nil?
+
+      attrs += additional_attrs
+      start_tag = make_start_tag(indent, next_indent, attrs)
+
+      if block
+        content = block.call(next_indent)
+      else
+        content = []
+      end
+
+      if content.is_a?(String)
+        content = [content]
+        start_tag << ">"
+        end_tag = "</#{full_name}>"
+      else
+        content = content.reject{|x| x.empty?}
+        if content.empty?
+          end_tag = "/>"
+        else
+          start_tag << ">\n"
+          end_tag = "\n#{indent}</#{full_name}>"
+        end
+      end
+      
+      start_tag + content.join("\n") + end_tag
+    end
+
+    def make_start_tag(indent, next_indent, attrs)
+      start_tag = ["#{indent}<#{full_name}"]
+      unless attrs.empty?
+        start_tag << attrs.collect do |key, value|
+          %Q[#{h key}="#{h value}"]
+        end.join("\n#{next_indent}")
+      end
+      start_tag.join(" ")
+    end
+
+    def collect_attrs
+      _attrs.collect do |name, required, alias_name|
+        value = __send__(alias_name || name)
+        return nil if required and value.nil?
+        [name, value]
+      end.reject do |name, value|
+        value.nil?
+      end
+    end
+    
+    def tag_name_with_prefix(prefix)
+      "#{prefix}:#{tag_name}"
+    end
+    
+    def calc_indent
+      INDENT * (self.class.indent_size)
+    end
+
+    def maker_target(maker)
+      nil
+    end
+    
+    def setup_maker_attributes(target)
+    end
+    
+    def setup_maker_element(target)
+      self.class.need_initialize_variables.each do |var|
+        setter = "#{var}="
+        if target.respond_to?(setter)
+          target.__send__(setter, __send__(var))
+        end
+      end
+    end
+    
+    def setup_maker_elements(parent)
+      self.class.have_children_elements.each do |name, plural_name|
+        real_name = name.sub(/^[^_]+_/, '')
+        if parent.respond_to?(plural_name)
+          target = parent.__send__(plural_name)
+          __send__(plural_name).each do |elem|
+            elem.__send__("setup_maker", target)
+          end
+        end
+      end
+    end
+
+    def set_next_element(prefix, tag_name, next_element)
+      klass = next_element.class
+      prefix = ""
+      prefix << "#{klass.required_prefix}_" if klass.required_prefix
+      if self.class.plural_forms.has_key?(tag_name)
+        ary = __send__("#{prefix}#{self.class.plural_forms[tag_name]}")
+        ary << next_element
+      else
+        __send__("#{prefix}#{tag_name}=", next_element)
+      end
+    end
+    
     # not String class children.
     def children
       []
@@ -507,23 +668,23 @@ EOC
     end
 
     def validate_attribute
-      _attrs.each do |a_name, required|
-        if required and send(a_name).nil?
-          raise MissingAttributeError.new(self.class.tag_name, a_name)
+      _attrs.each do |a_name, required, alias_name|
+        if required and __send__(alias_name || a_name).nil?
+          raise MissingAttributeError.new(tag_name, a_name)
         end
       end
     end
 
     def other_element(convert, indent='')
-      rv = ''
+      rv = []
       private_methods.each do |meth|
         if /\A([^_]+)_[^_]+_elements?\z/ =~ meth and
             self.class::NSPOOL.has_key?($1)
-          res = send(meth, convert)
-          rv << "#{indent}#{res}\n" if /\A\s*\z/ !~ res
+          res = __send__(meth, convert)
+          rv << "#{indent}#{res}" if /\A\s*\z/ !~ res
         end
       end
-      rv
+      rv.join("\n")
     end
 
     def _validate(tags, model=self.class.model)
@@ -626,19 +787,12 @@ EOC
       rv
     end
 
-    private
-    def calc_indent
-      INDENT * (self.class.indent_size)
-    end
-    
-    def remove_empty_newline(string)
-      string.gsub(/^\s*$(?:\r?\n?)/, '')
-    end
-    
   end
 
   module RootElementMixin
 
+    include XMLStyleSheetMixin
+    
     attr_reader :output_encoding
 
     def initialize(rss_version, version=nil, encoding=nil, standalone=nil)
@@ -655,26 +809,50 @@ EOC
       self.converter = Converter.new(@output_encoding, @encoding)
     end
 
+    def setup_maker(maker)
+      maker.version = version
+      maker.encoding = encoding
+      maker.standalone = standalone
+
+      xml_stylesheets.each do |xss|
+        xss.setup_maker(maker)
+      end
+
+      setup_maker_elements(maker)
+    end
+    
     private
+    def tag(indent, attrs, &block)
+      rv = xmldecl + xml_stylesheet_pi
+      rv << super(indent, attrs, &block)
+      rv
+    end
+
     def xmldecl
       rv = %Q[<?xml version="#{@version}"]
       if @output_encoding or @encoding
         rv << %Q[ encoding="#{@output_encoding or @encoding}"]
       end
-      rv << %Q[ standalone="#{@standalone}"] if @standalone
-      rv << '?>'
+      rv << %Q[ standalone="yes"] if @standalone
+      rv << "?>\n"
       rv
     end
     
-    def ns_declaration(indent)
-      rv = ''
-      self.class::NSPOOL.each do |prefix, uri|
+    def ns_declarations
+      self.class::NSPOOL.collect do |prefix, uri|
         prefix = ":#{prefix}" unless prefix.empty?
-        rv << %Q|\n#{indent}xmlns#{prefix}="#{html_escape(uri)}"|
+        ["xmlns#{prefix}", uri]
       end
-      rv
     end
     
+    def setup_maker_elements(maker)
+      channel.setup_maker(maker) if channel
+      image.setup_maker(maker) if image
+      textinput.setup_maker(maker) if textinput
+      items.each do |item|
+        item.setup_maker(maker)
+      end
+    end
   end
 
 end
diff --git a/lib/rss/trackback.rb b/lib/rss/trackback.rb
index e276305ec1..8bc1ee5ad5 100644
--- a/lib/rss/trackback.rb
+++ b/lib/rss/trackback.rb
@@ -9,7 +9,16 @@ module RSS
   RDF.install_ns(TRACKBACK_PREFIX, TRACKBACK_URI)
   Rss.install_ns(TRACKBACK_PREFIX, TRACKBACK_URI)
 
-  module BaseTrackBackModel
+  module TrackBackUtils
+    private
+    def new_with_value_if_need(klass, value)
+      if value.is_a?(klass)
+        value
+      else
+        klass.new(value)
+      end
+    end
+          
     def trackback_validate(tags)
       counter = {}
       %w(ping about).each do |x|
@@ -31,24 +40,78 @@ module RSS
       end
     end
   end
-
-  module TrackBackModel10
-    extend BaseModel
-    include BaseTrackBackModel
-
-    def self.append_features(klass)
+  
+  module BaseTrackBackModel
+    def append_features(klass)
       super
 
       unless klass.class == Module
+        klass.__send__(:include, TrackBackUtils)
+
         %w(ping).each do |x|
-          klass.install_have_child_element("#{TRACKBACK_PREFIX}_#{x}")
+          var_name = "#{TRACKBACK_PREFIX}_#{x}"
+          klass_name = x.capitalize
+          klass.install_have_child_element(var_name)
+          klass.module_eval(<<-EOC, __FILE__, __LINE__)
+            remove_method :#{var_name}
+            def #{var_name}
+              @#{var_name} and @#{var_name}.value
+            end
+
+            remove_method :#{var_name}=
+            def #{var_name}=(value)
+              @#{var_name} = new_with_value_if_need(#{klass_name}, value)
+            end
+          EOC
         end
         
-        %w(about).each do |x|
-          klass.install_have_children_element("#{TRACKBACK_PREFIX}_#{x}")
+        [%w(about s)].each do |name, postfix|
+          var_name = "#{TRACKBACK_PREFIX}_#{name}"
+          klass_name = name.capitalize
+          klass.install_have_children_element(var_name)
+          klass.module_eval(<<-EOC, __FILE__, __LINE__)
+            remove_method :#{var_name}
+            def #{var_name}(*args)
+              if args.empty?
+                @#{var_name}.first and @#{var_name}.first.value
+              else
+                ret = @#{var_name}.send("[]", *args)
+                if ret.is_a?(Array)
+                  ret.collect {|x| x.value}
+                else
+                  ret.value
+                end
+              end
+            end
+
+            remove_method :#{var_name}=
+            remove_method :set_#{var_name}
+            def #{var_name}=(*args)
+              if args.size == 1
+                item = new_with_value_if_need(#{klass_name}, args[0])
+                @#{var_name}.push(item)
+              else
+                new_val = args.last
+                if new_val.is_a?(Array)
+                  new_val = new_value.collect do |val|
+                    new_with_value_if_need(#{klass_name}, val)
+                  end
+                else
+                  new_val = new_with_value_if_need(#{klass_name}, new_val)
+                end
+                @#{var_name}.send("[]=", *(args[0..-2] + [new_val]))
+              end
+            end
+            alias set_#{var_name} #{var_name}=
+          EOC
         end
       end
     end
+  end
+
+  module TrackBackModel10
+    extend BaseModel
+    extend BaseTrackBackModel
 
     class Ping < Element
       include RSS10
@@ -71,26 +134,28 @@ module RSS
         install_get_attribute(name, uri, required)
       end
 
+      alias_method(:value, :resource)
+      alias_method(:value=, :resource=)
+      
       def initialize(resource=nil)
         super()
         @resource = resource
       end
 
+      def full_name
+        tag_name_with_prefix(TRACKBACK_PREFIX)
+      end
+      
       def to_s(convert=true, indent=calc_indent)
-        if @resource
-          rv = %Q[#{indent}<#{TRACKBACK_PREFIX}:ping ]
-          rv << %Q[#{::RSS::RDF::PREFIX}:resource="#{h @resource}"/>]
-          rv = @converter.convert(rv) if convert and @converter
-          rv
-        else
-          ''
-        end
+        rv = tag(indent)
+        rv = @converter.convert(rv) if convert and @converter
+        rv
       end
 
       private
       def _attrs
         [
-          ["resource", true],
+          ["#{::RSS::RDF::PREFIX}:resource", true, "resource"],
         ]
       end
 
@@ -117,118 +182,45 @@ module RSS
         install_get_attribute(name, uri, required)
       end
 
+      alias_method(:value, :resource)
+      alias_method(:value=, :resource=)
+      
       def initialize(resource=nil)
         super()
         @resource = resource
       end
 
+      def full_name
+        tag_name_with_prefix(TRACKBACK_PREFIX)
+      end
+      
       def to_s(convert=true, indent=calc_indent)
-        if @resource
-          rv = %Q[#{indent}<#{TRACKBACK_PREFIX}:about ]
-          rv << %Q[#{::RSS::RDF::PREFIX}:resource="#{h @resource}"/>]
-          rv = @converter.convert(rv) if convert and @converter
-          rv
-        else
-          ''
-        end
+        rv = tag(indent)
+        rv = @converter.convert(rv) if convert and @converter
+        rv
       end
 
       private
       def _attrs
         [
-          ["resource", true],
+          ["#{::RSS::RDF::PREFIX}:resource", true, "resource"],
         ]
       end
 
-    end
-  end
-
-  module TrackBackModel20
-    include BaseTrackBackModel
-    extend BaseModel
-
-    def self.append_features(klass)
-      super
-
-      unless klass.class == Module
-        %w(ping).each do |x|
-          var_name = "#{TRACKBACK_PREFIX}_#{x}"
-          klass.install_have_child_element(var_name)
-          klass.module_eval(<<-EOC)
-            alias _#{var_name} #{var_name}
-            def #{var_name}
-              @#{var_name} and @#{var_name}.content
-            end
-
-            alias _#{var_name}= #{var_name}=
-            def #{var_name}=(content)
-              @#{var_name} = new_with_content_if_need(#{x.capitalize}, content)
-            end
-          EOC
-        end
-        
-        [%w(about s)].each do |x, postfix|
-          var_name = "#{TRACKBACK_PREFIX}_#{x}"
-          klass.install_have_children_element(var_name)
-          klass.module_eval(<<-EOC)
-            alias _#{var_name}#{postfix} #{var_name}#{postfix}
-            def #{var_name}#{postfix}
-              @#{var_name}.collect {|x| x.content}
-            end
-
-            alias _#{var_name} #{var_name}
-            def #{var_name}(*args)
-              if args.empty?
-                @#{var_name}.first and @#{var_name}.first.content
-              else
-                ret = @#{var_name}.send("[]", *args)
-                if ret.is_a?(Array)
-                  ret.collect {|x| x.content}
-                else
-                  ret.content
-                end
-              end
-            end
-
-            alias _#{var_name}= #{var_name}=
-            alias _set_#{var_name} set_#{var_name}
-            def #{var_name}=(*args)
-              if args.size == 1
-                item = new_with_content_if_need(#{x.capitalize}, args[0])
-                @#{var_name}.push(item)
-              else
-                new_val = args.last
-                if new_val.is_a?(Array)
-                  new_val = new_value.collect do |val|
-                    new_with_content_if_need(#{x.capitalize}, val)
-                  end
-                else
-                  new_val = new_with_content_if_need(#{x.capitalize}, new_val)
-                end
-                @#{var_name}.send("[]=", *(args[0..-2] + [new_val]))
-              end
-            end
-            alias set_#{var_name} #{var_name}=
-          EOC
-        end
+      def maker_target(abouts)
+        abouts.new_about
       end
-    end
 
-    private
-    def new_with_content(klass, content)
-      obj = klass.new
-      obj.content = content
-      obj
-    end
-
-    def new_with_content_if_need(klass, content)
-      if content.is_a?(klass)
-        content
-      else
-        new_with_content(klass, content)
+      def setup_maker_attributes(about)
+        about.resource = self.resource
       end
+      
     end
+  end
 
+  module TrackBackModel20
+    extend BaseModel
+    extend BaseTrackBackModel
 
     class Ping < Element
       include RSS09
@@ -247,18 +239,18 @@ module RSS
 
       end
       
-      def to_s(convert=true, indent=calc_indent)
-        if @content
-          rv = %Q[#{indent}<#{TRACKBACK_PREFIX}:ping>]
-          rv << h(@content)
-          rv << %Q[</#{TRACKBACK_PREFIX}:ping>]
-          rv = @converter.convert(rv) if convert and @converter
-          rv
-        else
-          ''
-        end
-      end
+      alias_method(:value, :content)
+      alias_method(:value=, :content=)
 
+      def initialize(content=nil)
+        super()
+        @content = content
+      end
+      
+      def full_name
+        tag_name_with_prefix(TRACKBACK_PREFIX)
+      end
+      
     end
 
     class About < Element
@@ -277,19 +269,19 @@ module RSS
         end
 
       end
+
+      alias_method(:value, :content)
+      alias_method(:value=, :content=)
+
+      def initialize(content=nil)
+        super()
+        @content = content
+      end
       
-      def to_s(convert=true, indent=calc_indent)
-        if @content
-          rv = %Q[#{indent}<#{TRACKBACK_PREFIX}:about>]
-          rv << h(@content)
-          rv << %Q[</#{TRACKBACK_PREFIX}:about>]
-          rv = @converter.convert(rv) if convert and @converter
-          rv
-        else
-          ''
-        end
+      def full_name
+        tag_name_with_prefix(TRACKBACK_PREFIX)
       end
-
+      
     end
   end
 
diff --git a/lib/rss/xml-stylesheet.rb b/lib/rss/xml-stylesheet.rb
index c51c0dc71a..05602eee9b 100644
--- a/lib/rss/xml-stylesheet.rb
+++ b/lib/rss/xml-stylesheet.rb
@@ -84,6 +84,13 @@ module RSS
       @alternate
     end
 
+    def setup_maker(maker)
+      xss = maker.xml_stylesheets.new_xml_stylesheet
+      ATTRIBUTES.each do |attr|
+        xss.__send__("#{attr}=", __send__(attr))
+      end
+    end
+    
     private
     def guess_type(filename)
       /\.([^.]+)$/ =~ filename
diff --git a/lib/rss/xmlscanner.rb b/lib/rss/xmlscanner.rb
index 472ca93523..c5a11bad18 100644
--- a/lib/rss/xmlscanner.rb
+++ b/lib/rss/xmlscanner.rb
@@ -45,7 +45,7 @@ module RSS
     end
 
     def on_xmldecl_end
-      xmldecl(@version, @encoding, @standalone)
+      xmldecl(@version, @encoding, @standalone == "yes")
     end
 
     alias_method(:on_pi, :instruction)