lib/active_support/callbacks.rb in activesupport-4.2.5 vs lib/active_support/callbacks.rb in activesupport-4.2.5.1

@@ -768,10 +768,10 @@
       # `!`, `?` or `=`.
       def define_callbacks(*names)
         options = names.extract_options!
 
         names.each do |name|
-          class_attribute "_#{name}_callbacks"
+          class_attribute "_#{name}_callbacks", instance_writer: false
           set_callbacks name, CallbackChain.new(name, options)
 
           module_eval <<-RUBY, __FILE__, __LINE__ + 1
             def _run_#{name}_callbacks(&block)
               __run_callbacks__(_#{name}_callbacks, &block)