3 files changed, 11 insertions, 7 deletions
diff --git a/actionpack/lib/action_controller/base.rb b/actionpack/lib/action_controller/base.rb
index 2c91266f6f..1ceb58711b 100755
--- a/actionpack/lib/action_controller/base.rb
+++ b/actionpack/lib/action_controller/base.rb
@@ -27,6 +27,8 @@ module ActionController #:nodoc:
   end
   class MissingFile < ActionControllerError #:nodoc:
   end
+  class RenderError < ActionControllerError #:nodoc:
+  end
   class SessionOverflowError < ActionControllerError #:nodoc:
     DEFAULT_MESSAGE = 'Your session data is larger than the data column in which it is to be stored. You must increase the size of your data column if you intend to store large data.'
 
diff --git a/actionpack/lib/action_controller/mime_responds.rb b/actionpack/lib/action_controller/mime_responds.rb
index fd9af05905..21905b26c8 100644
--- a/actionpack/lib/action_controller/mime_responds.rb
+++ b/actionpack/lib/action_controller/mime_responds.rb
@@ -108,11 +108,9 @@ module ActionController #:nodoc:
     end
     
     class Responder #:nodoc:
-      DEFAULT_BLOCKS = {
-        :html    => 'Proc.new { render }',
-        :js      => 'Proc.new { render :action => "#{action_name}.rjs" }',
-        :xml     => 'Proc.new { render :action => "#{action_name}.rxml" }'
-      }
+      DEFAULT_BLOCKS = [:html, :js, :xml].inject({}) do |blocks, ext|
+        blocks.update ext => %(Proc.new { render :action => "\#{action_name}.r#{ext}" })
+      end      
       
       def initialize(block_binding)
         @block_binding = block_binding
@@ -134,7 +132,11 @@ module ActionController #:nodoc:
         if block_given?
           @responses[mime_type] = block
         else
-          @responses[mime_type] = eval(DEFAULT_BLOCKS[mime_type.to_sym], @block_binding)
+          if source = DEFAULT_BLOCKS[mime_type.to_sym]
+            @responses[mime_type] = eval(source, @block_binding)            
+          else
+            raise ActionController::RenderError, "Expected a block but none was given for custom mime handler #{mime_type}"
+          end
         end
       end
 
diff --git a/actionpack/lib/action_controller/mime_type.rb b/actionpack/lib/action_controller/mime_type.rb
index dccc32bb91..f2b8e32546 100644
--- a/actionpack/lib/action_controller/mime_type.rb
+++ b/actionpack/lib/action_controller/mime_type.rb
@@ -34,7 +34,7 @@ module Mime
       def register(string, symbol, synonyms = [])
         Mime.send :const_set, symbol.to_s.upcase, Type.new(string, symbol, synonyms)
         SET << Mime.send(:const_get, symbol.to_s.upcase)
-        LOOKUP[string] = EXTENSION_LOOKUP[symbol.to_s] = SET.last
+        LOOKUP[string] = EXTENSION_LOOKUP[symbol.to_s] = SET.last        
       end
 
       def parse(accept_header)