Symbolize all the style keys

This will prevent a pitfall as sometime the style's name can be a string.

lib/paperclip/attachment.rb

@@ -90,6 +90,7 @@ module Paperclip
       ensure_required_accessors!
       file = Paperclip.io_adapters.for(uploaded_file)
 
+      @options[:only_process].map!(&:to_sym)
       self.clear(*@options[:only_process])
       return nil if file.nil?
 
@@ -164,7 +165,7 @@ module Paperclip
       if styling_option.respond_to?(:call) || !@normalized_styles
         @normalized_styles = ActiveSupport::OrderedHash.new
         (styling_option.respond_to?(:call) ? styling_option.call(self) : styling_option).each do |name, args|
-          @normalized_styles[name] = Paperclip::Style.new(name, args.dup, self)
+          @normalized_styles[name.to_sym] = Paperclip::Style.new(name.to_sym, args.dup, self)
         end
       end
       @normalized_styles
@@ -375,6 +376,7 @@ module Paperclip
 
     def post_process(*style_args) #:nodoc:
       return if @queued_for_write[:original].nil?
+
       instance.run_paperclip_callbacks(:post_process) do
         instance.run_paperclip_callbacks(:"#{name}_post_process") do
           post_process_styles(*style_args)

test/integration_test.rb

@@ -439,11 +439,50 @@ class IntegrationTest < Test::Unit::TestCase
       @dummy.avatar = @file
     end
 
+    teardown { @file.close }
+
     should "should not error when saving" do
       @dummy.save!
     end
   end
 
+  context "A model with an attachment with hash in file name" do
+    setup do
+      @settings = { :styles => { :thumb => "50x50#" },
+        :path => ":rails_root/public/system/:attachment/:id_partition/:style/:hash.:extension",
+        :url => "/system/:attachment/:id_partition/:style/:hash.:extension",
+        :hash_secret => "somesecret" }
+
+      rebuild_model @settings
+
+      @file = File.new(File.join(File.dirname(__FILE__), "fixtures", "5k.png"), 'rb')
+      @dummy = Dummy.create! :avatar => @file
+    end
+
+    teardown do
+      @file.close
+    end
+
+    should "be accessible" do
+      assert File.exists?(@dummy.avatar.path(:original))
+      assert File.exists?(@dummy.avatar.path(:thumb))
+    end
+
+    context "when new style is added" do
+      setup do
+        @dummy.avatar.options[:styles][:mini] = "25x25#"
+        @dummy.avatar.instance_variable_set :@normalized_styles, nil
+        @dummy.avatar.reprocess! 'mini'
+      end
+
+      should "make all the styles accessible" do
+        assert File.exists?(@dummy.avatar.path(:original))
+        assert File.exists?(@dummy.avatar.path(:thumb))
+        assert File.exists?(@dummy.avatar.path(:mini))
+      end
+    end
+  end
+
   if ENV['S3_TEST_BUCKET']
     def s3_files_for attachment
       [:thumb, :medium, :large, :original].inject({}) do |files, style|
@@ -604,4 +643,3 @@ class IntegrationTest < Test::Unit::TestCase
     end
   end
 end
-