Set up slug.rb for obvious method extractions.

lib/slug.rb

@@ -6,20 +6,24 @@
 module Slug
 
   def self.for(string)
-
-    str = string.dup
-    str.gsub!(/^\s+|\s+$/, '')
-    str.downcase!
-
+    str = string.dup.strip.downcase
+    
     # The characters we want to replace with a hyphen
     str.tr!("·/_,:;.", "\-")
 
     # Convert to ASCII or remove if transliteration is unknown.
     str = ActiveSupport::Inflector.transliterate(str, '')
-
+    
+    # Remove everything except alphanumberic, space, and hyphen characters.
     str.gsub!(/[^a-z0-9 -]/, '')
+    
+    # Replace multiple spaces with one hyphen.
     str.gsub!(/\s+/, '-')
+    
+    # Replace multiple hyphens with one hyphen.
     str.gsub!(/\-+/, '-')
+    
+    # Remove leading and trailing hyphens
     str.gsub!(/^-|-$/, '')
 
     str