* lib/observer.rb: [DOC] Clarify default observer method.

By @edward [Fixes GH-450] https://github.com/ruby/ruby/pull/450


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@43743 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,8 @@
+Thu Nov 21 13:40:20 2013  Zachary Scott  <e@zzak.io>
+
+	* lib/observer.rb: [DOC] Clarify default observer method.
+	  By @edward [Fixes GH-450] https://github.com/ruby/ruby/pull/450
+
 Thu Nov 21 13:32:53 2013  Zachary Scott  <e@zzak.io>
 
 	* ext/openssl/ossl_engine.c: [DOC] Documentation for OpenSSL::Engine

lib/observer.rb

@@ -15,13 +15,14 @@
 # module, which provides the methods for managing the associated observer
 # objects.
 #
-# The observers must implement a method called +update+ to receive
-# notifications.
-#
 # The observable object must:
 # * assert that it has +#changed+
 # * call +#notify_observers+
 #
+# An observer subscribes to updates using Observable#add_observer, which also
+# specifies the method called via #notify_observers. The default method for
+# #notify_observers is #update.
+#
 # === Example
 #
 # The following example demonstrates this nicely.  A +Ticker+, when run,