Switched interpolations module from module methods to instance methods

lib/paperclip/interpolations.rb

 module Paperclip
   module Interpolations
+    extend self
+
     def self.[]= name, block
-      (class << self; self; end).class_eval do
       define_method(name, &block)
     end
-    end
 
     def self.[] name
       method(name)
     end
 
     def self.all
-      (singleton_methods - ["[]=", "[]", "all"]).sort
+      self.instance_methods(false).sort
     end
 
-    def self.rails_root attachment, style
+    def rails_root attachment, style
       RAILS_ROOT
     end
 
-    def self.rails_env attachment, style
+    def rails_env attachment, style
       RAILS_ENV
     end
 
-    def self.class attachment, style
+    def class attachment, style
       attachment.instance.class.to_s.underscore.pluralize
     end
 
-    def self.basename attachment, style
+    def basename attachment, style
       attachment.original_filename.gsub(/#{File.extname(attachment.original_filename)}$/, "")
     end
 
-    def self.extension attachment, style 
+    def extension attachment, style 
       ((style = attachment.styles[style]) && style[:format]) ||
         File.extname(attachment.original_filename).gsub(/^\.+/, "")
     end
 
-    def self.id attachment, style
+    def id attachment, style
       attachment.instance.id
     end
 
-    def self.id_partition attachment, style
+    def id_partition attachment, style
       ("%09d" % attachment.instance.id).scan(/\d{3}/).join("/")
     end
 
-    def self.attachment attachment, style
+    def attachment attachment, style
       attachment.name.to_s.downcase.pluralize
     end
 
-    def self.style attachment, style
+    def style attachment, style
       style || attachment.default_style
     end
   end