Update :scope to be coerced into an Array if it is not already

* Minor doc/spec update to show this new behaviour

README.rdoc

@@ -57,7 +57,7 @@ having their own todo-lists.
     belongs_to :user
 
     # here we define that this should be a list, scoped on :user_id
-    is :list, :scope => [:user_id]
+    is :list, :scope => :user_id  # you may also pass in multiple properties, eg [ :user_id, :title ]
   end
 
 Once we have our Users and Lists, we might want to work with...

lib/dm-is-list/is/list.rb

@@ -235,9 +235,9 @@ module List
       # custom :field
       #
       # @example [Usage]
-      #   is :list  # put this in your model to make it act as a list.
-      #   is :list, :scope => [:user_id] # you can also define scopes
-      #   is :list, :scope => [:user_id, :context_id] # also works with multiple params
+      #   is :list                                      # put this in your model to make it act as a list.
+      #   is :list, :scope => :user_id                  # you can also define scopes
+      #   is :list, :scope => [ :user_id, :context_id ] # also works with multiple params
       #
       # @param options <Hash> a hash of options
       #
@@ -247,6 +247,9 @@ module List
       def is_list(options={})
         options = { :scope => [], :first => 1 }.merge(options)
 
+        # coerce the scope into an Array
+        options[:scope] = Array(options[:scope])
+
         extend  DataMapper::Is::List::ClassMethods
         include DataMapper::Is::List::InstanceMethods
 

spec/spec_helper.rb

@@ -23,7 +23,7 @@ class Todo
 
   belongs_to :user
 
-  is :list, :scope => [:user_id]
+  is :list, :scope => :user_id
 end
 
 module TodoListHelper