1 files changed, 16 insertions, 4 deletions
diff --git a/activemodel/lib/active_model/attribute_methods.rb b/activemodel/lib/active_model/attribute_methods.rb
index 588976f1d4..f04829ef09 100644
--- a/activemodel/lib/active_model/attribute_methods.rb
+++ b/activemodel/lib/active_model/attribute_methods.rb
@@ -53,7 +53,6 @@ module ActiveModel
   module AttributeMethods
     extend ActiveSupport::Concern
 
-    # Declare and check for suffixed attribute methods.
     module ClassMethods
       # Defines an "attribute" method (like +inheritance_column+ or
       # +table_name+). A new (class) method will be created with the
@@ -90,13 +89,20 @@ module ActiveModel
       #   # => 'address_id'
       def define_attr_method(name, value=nil, &block)
         sing = singleton_class
-        sing.send :alias_method, "original_#{name}", name
+        sing.class_eval <<-eorb, __FILE__, __LINE__ + 1
+          if method_defined?(:original_#{name})
+            undef :original_#{name}
+          end
+          alias_method :original_#{name}, :#{name}
+        eorb
         if block_given?
           sing.send :define_method, name, &block
         else
           # use eval instead of a block to work around a memory leak in dev
           # mode in fcgi
-          sing.class_eval "def #{name}; #{value.to_s.inspect}; end"
+          sing.class_eval <<-eorb, __FILE__, __LINE__ + 1
+            def #{name}; #{value.to_s.inspect}; end
+          eorb
         end
       end
 
@@ -257,8 +263,13 @@ module ActiveModel
               if respond_to?(generate_method)
                 send(generate_method, attr_name)
               else
+                method_name = matcher.method_name(attr_name)
+
                 generated_attribute_methods.module_eval <<-STR, __FILE__, __LINE__+1
-                  def #{matcher.method_name(attr_name)}(*args)
+                  if method_defined?(:#{method_name})
+                    undef :#{method_name}
+                  end
+                  def #{method_name}(*args)
                     send(:#{matcher.method_missing_target}, '#{attr_name}', *args)
                   end
                 STR
@@ -286,6 +297,7 @@ module ActiveModel
         end
       end
 
+      # Returns true if the attribute methods defined have been generated.
       def attribute_methods_generated?
         @attribute_methods_generated ||= nil
       end