Added new symbol-driven approach to activating observers with Base#observer [DHH]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@2326 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

actionpack/CHANGELOG

 *SVN*
 
-* Fixed that auto_discovery_link_tag couldn't take a string as the URL
+* Fix open/save dialog in IE not opening files send with send_file/send_data, #2279 [Thomas Fuchs]
 
-* Fixed problem with send_file and WEBrick using stdout #1812
+* Fixed that auto_discovery_link_tag couldn't take a string as the URL [DHH]
+
+* Fixed problem with send_file and WEBrick using stdout #1812 [DHH]
 
 * Optimized tag_options to not sort keys, which is no longer necessary when assert_dom_equal and friend is available #1995 [skae]
 

activerecord/CHANGELOG

 *SVN*
 
-* Wrap :conditions in parentheses to prevent problems with OR's #1871
+* Added new symbol-driven approach to activating observers with Base#observer [DHH]. Example:
 
-* Allow the postgresql adapter to work with the SchemaDumper.
+    ActiveRecord::Base.observer(:cacher, :garbage_collector)
+  
+  ...which is the same as doing:
+  
+    [ Cacher.instance, GarbageCollector.instance ]
+
+* Added AbstractAdapter#select_value and AbstractAdapter#select_values as convenience methods for selecting single values, instead of hashes, of the first column in a SELECT #2283 [solo@gatelys.com]
+
+* Wrap :conditions in parentheses to prevent problems with OR's #1871 [Jamis Buck]
+
+* Allow the postgresql adapter to work with the SchemaDumper. [Jamis Buck]
 
-* Add ActiveRecord::SchemaDumper for dumping a DB schema to a pure-ruby file, making it easier to consolidate large migration lists and port database schemas between databases.
+* Add ActiveRecord::SchemaDumper for dumping a DB schema to a pure-ruby file, making it easier to consolidate large migration lists and port database schemas between databases. [Jamis Buck]
 
 * Fixed migrations for Windows when using more than 10 [David Naseby]
 

activerecord/lib/active_record.rb

@@ -54,6 +54,7 @@
   include ActiveRecord::Validations
   include ActiveRecord::Locking
   include ActiveRecord::Callbacks
+  include ActiveRecord::Observing
   include ActiveRecord::Timestamp
   include ActiveRecord::Associations
   include ActiveRecord::Aggregations

activerecord/lib/active_record/observer.rb

 require 'singleton'
 
 module ActiveRecord
+  module Observing # :nodoc:
+    def self.append_features(base)
+      super
+      base.extend(ClassMethods)
+    end
+
+    module ClassMethods
+      # Activates the observers assigned. Examples:
+      #
+      #   # Calls PersonObserver.instance and returns the instance of that observer
+      #   ActiveRecord::Base.observer(:person_observer)
+      #
+      #   # Calls Cacher.instance and GarbageCollector.instance 
+      #   # and returns an array with instances of both
+      #   ActiveRecord::Base.observer(:cacher, :garbage_collector)
+      #
+      #   # Same as above, just using explicit class references
+      #   ActiveRecord::Base.observer(Cacher, GarbageCollector)
+      def observer(*observers)
+        observers = [ observers ].flatten.collect do |observer| 
+          observer.is_a?(Symbol) ? 
+            observer.to_s.camelize.constantize.instance :
+            observer.instance
+        end
+        
+        observers.size > 1 ? observers : observers.first
+      end
+    end
+  end
+
   # Observer classes respond to lifecycle callbacks to implement trigger-like
   # behavior outside the original class. This is a great way to reduce the
   # clutter that normally comes when the model class is burdened with
@@ -48,7 +78,8 @@ module ActiveRecord
   # == Triggering Observers
   # 
   # In order to activate an observer, you need to call Observer.instance. In Rails, this can be done in controllers
-  # using the short-hand of for example observer :comment_observer.
+  # using the short-hand of for example observer :comment_observer. Or directly from Active Record, with
+  # ActiveRecord::Base.observer(:comment_observer).
   class Observer
     include Singleton
 

activerecord/test/lifecycle_test.rb

@@ -65,7 +65,7 @@ def test_before_destroy
   end
   
   def test_after_save
-    topic_observer = TopicManualObserver.instance
+    topic_observer = ActiveRecord::Base.observer(:topic_manual_observer)
 
     topic = Topic.find(1)
     topic.title = "hello"
@@ -76,7 +76,7 @@ def test_after_save
   end
   
   def test_observer_update_on_save
-    topic_observer = TopicManualObserver.instance
+    topic_observer = ActiveRecord::Base.observer(TopicManualObserver)
 
     topic = Topic.find(1)    
     assert topic_observer.has_been_notified?

railties/environments/environment.rb

@@ -18,9 +18,6 @@
   # (by default production uses :info, the others :debug)
   # config.log_level = :debug
 
-  # Only include the connection adapters you're actually going to use
-  # config.connection_adapters = %w( mysql postgresql sqlite sqlserver db2 oci )
-
   # Use the database for sessions instead of the file system
   # (create the session table with 'rake create_sessions_table')
   # config.action_controller.session_store = :active_record_store
@@ -29,6 +26,9 @@
   # (remember to create the caching directory and make it readable to the application)
   # config.action_controller.fragment_cache_store = :file_store, "#{RAILS_ROOT}/cache"
 
+  # Activate observers that should always be running
+  # config.active_record.observer :cacher, :garbage_collector
+
   # Make Active Record use UTC-base instead of local time
   # config.active_record.default_timezone = :utc