let people deviate from the only sensible tag delimiter

lib/is_taggable.rb

@@ -5,6 +5,14 @@
 
 module IsTaggable
   class TagList < Array
+    cattr_accessor :delimiter
+    @@delimiter = ', '
+
+    def initialize(list)
+      list = list.is_a?(Array) ? list : list.split(@@delimiter)
+      super
+    end
+
     def to_s
       join(', ')
     end
@@ -38,7 +46,7 @@ def self.included(klass)
 
     module InstanceMethods
       def set_tag_list(kind, list)
-        tag_list = TagList.new(list.is_a?(Array) ? list : list.split(', '))
+        tag_list = TagList.new(list)
         instance_variable_set(tag_list_name_for_kind(kind), tag_list)
       end
 

test/is_taggable_test.rb

@@ -13,6 +13,13 @@
     n = Comment.new :tag_list => "is_taggable, has 'tags' by default"
     n.tag_list
   end
+
+  expect ["one", "two"] do
+    IsTaggable::TagList.delimiter = " "
+    n = Comment.new :tag_list => "one two"
+    IsTaggable::TagList.delimiter = ", " # puts things back to avoid breaking following tests
+    n.tag_list
+  end
 
   expect ["something cool", "something else cool"] do
     p = Post.new :tag_list => "something cool, something else cool"