Reshuffle load order so that routes and observers are initialized after plugins and app initializers. Closes #10980 [rick, fxn]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@8787 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

2 files changed, 16 insertions, 0 deletions

diff --git a/activerecord/CHANGELOG b/activerecord/CHANGELOG
index c10bb9f416..b2e2a117fb 100644
--- a/activerecord/CHANGELOG
+++ b/activerecord/CHANGELOG
@@ -1,5 +1,7 @@
 *SVN*
 
+* Add note about how ActiveRecord::Observer classes are initialized in a Rails app. #10980 [fxn]
+
 * MySQL: omit text/blob defaults from the schema instead of using an empty string.  #10963 [mdeiters]
 
 * belongs_to supports :dependent => :destroy and :delete.  #10592 [Jonathan Viney]
diff --git a/activerecord/lib/active_record/observer.rb b/activerecord/lib/active_record/observer.rb
index cfdeae3592..6e4db637f5 100644
--- a/activerecord/lib/active_record/observer.rb
+++ b/activerecord/lib/active_record/observer.rb
@@ -125,6 +125,20 @@ module ActiveRecord
   #
   # Observers will not be invoked unless you define these in your application configuration.
   #
+  # == Loading
+  #
+  # Observers register themselves in the model class they observe, since it is the class that
+  # notifies them of events when they occur. As a side-effect, when an observer is loaded its
+  # corresponding model class is loaded.
+  # 
+  # Up to (and including) Rails 2.0.2 observers were instantiated between plugins and
+  # application initializers. Now observers are loaded after application initializers, 
+  # so observed models can make use of extensions.
+  # 
+  # If by any chance you are using observed models in the initialization you can still
+  # load their observers by calling <tt>ModelObserver.instance</tt> before. Observers are
+  # singletons and that call instantiates and registers them.
+  #
   class Observer
     include Singleton