Try replacing _erbout with @output_buffer

actionpack/lib/action_view/base.rb

@@ -178,10 +178,7 @@ def self.cache_template_extensions=(*args)
     # that alert()s the caught exception (and then re-raises it). 
     @@debug_rjs = false
     cattr_accessor :debug_rjs
-
-    @@erb_variable = '_erbout'
-    cattr_accessor :erb_variable
-
+
     attr_internal :request
 
     delegate :request_forgery_protection_token, :template, :params, :session, :cookies, :response, :headers,

actionpack/lib/action_view/helpers/capture_helper.rb

@@ -31,20 +31,13 @@ module CaptureHelper
       #   </body></html>
       #
       def capture(*args, &block)
-        # execute the block
-        begin
-          buffer = eval(ActionView::Base.erb_variable, block.binding)
-        rescue
-          buffer = nil
-        end
-
-        if buffer.nil?
-          capture_block(*args, &block).to_s
-        else
-          capture_erb_with_buffer(buffer, *args, &block).to_s
-        end
+        @output_buffer, old_buffer = '', @output_buffer
+        yield *args
+        @output_buffer
+      ensure
+        @output_buffer = old_buffer
       end
-      
+
       # Calling content_for stores a block of markup in an identifier for later use.
       # You can make subsequent calls to the stored content in other templates or the layout
       # by passing the identifier as an argument to <tt>yield</tt>.
@@ -121,40 +114,19 @@ def capture(*args, &block)
       # named <tt>@content_for_#{name_of_the_content_block}</tt>. The preferred usage is now
       # <tt><%= yield :footer %></tt>.
       def content_for(name, content = nil, &block)
-        existing_content_for = instance_variable_get("@content_for_#{name}").to_s
-        new_content_for      = existing_content_for + (block_given? ? capture(&block) : content)
-        instance_variable_set("@content_for_#{name}", new_content_for)
+        ivar = "@content_for_#{name}"
+        instance_variable_set("@content_for_#{name}", "#{instance_variable_get(ivar)}#{block_given? ? capture(&block) : content}")
       end
 
       private
-        def capture_block(*args, &block)
-          block.call(*args)
-        end
-
-        def capture_erb(*args, &block)
-          buffer = eval(ActionView::Base.erb_variable, block.binding)
-          capture_erb_with_buffer(buffer, *args, &block)
-        end
-
-        def capture_erb_with_buffer(buffer, *args, &block)
-          pos = buffer.length
-          block.call(*args)
-
-          # extract the block 
-          data = buffer[pos..-1]
-
-          # replace it in the original with empty string
-          buffer[pos..-1] = ''
-
-          data
-        end
-
         def erb_content_for(name, &block)
-          eval "@content_for_#{name} = (@content_for_#{name} || '') + capture_erb(&block)"
+          ivar = "@content_for_#{name}"
+          instance_variable_set(ivar, "#{instance_variable_get(ivar)}#{capture(&block)}")
         end
-
-        def block_content_for(name, &block)
-          eval "@content_for_#{name} = (@content_for_#{name} || '') + capture_block(&block)"
+
+        def block_content_for(name)
+          ivar = "@content_for_#{name}"
+          instance_variable_set(ivar, "#{instance_variable_get(ivar)}#{yield}")
         end
     end
   end

actionpack/lib/action_view/helpers/javascript_helper.rb

@@ -208,7 +208,7 @@ def array_or_string_for_javascript(option)
 
     private
       def block_is_within_action_view?(block)
-        eval("defined? _erbout", block.binding)
+        !@output_buffer.nil?
       end
     end
 

actionpack/lib/action_view/helpers/tag_helper.rb

@@ -126,7 +126,7 @@ def tag_options(options, escape = true)
         end
 
         def block_is_within_action_view?(block)
-          eval("defined? _erbout", block.binding)
+          !@output_buffer.nil?
         end
     end
   end

actionpack/lib/action_view/helpers/text_helper.rb

@@ -25,8 +25,12 @@ module TextHelper
       #       end
       #       # will either display "Logged in!" or a login link
       #   %>
-      def concat(string, binding)
-        eval(ActionView::Base.erb_variable, binding) << string
+      def concat(string, binding = nil)
+        if @output_buffer
+          @output_buffer << string
+        else
+          string
+        end
       end
 
       if RUBY_VERSION < '1.9'

actionpack/lib/action_view/template_handlers/erb.rb

@@ -43,13 +43,11 @@ class ERB < TemplateHandler
       include Compilable
 
       def compile(template)
-        ::ERB.new(template.source, nil, @view.erb_trim_mode).src
+        ::ERB.new(template.source, nil, @view.erb_trim_mode, '@output_buffer').src
       end
 
       def cache_fragment(block, name = {}, options = nil) #:nodoc:
-        @view.fragment_for(block, name, options) do
-          eval(ActionView::Base.erb_variable, block.binding)
-        end
+        @view.fragment_for(block, name, options) { @view.output_buffer }
       end
     end
   end