Aliasing AR attributes

Hey,

I'd like to add some "magic" functionality to some model by chain
aliasing an attributes setter method like this:
class Thing < ActiveRecord::Base
def registration_with_upcase=(r)
    self.registration_without_upcase=(r.upcase)
  end
  alias_method_chain "registration=", :upcase
end
p = Plane.new
p.destroy
Plane.class_eval <<-eos
  def registration_with_upcase=(r)
    self.registration_without_upcase=(r.upcase)
  end
  alias_method_chain "registration=", :upcase
eos

Argh sorry...
Again:
Hey,

I'd like to add some "magic" functionality to some model by chain
aliasing an attributes setter method like this:
class Thing < ActiveRecord::Base
def name_with_upcase=(r)
    self.name_without_upcase=(r.upcase)
  end
  alias_method_chain "name=", :upcase
end

This (on script/console) gives me this error:
NameError: /usr/lib/ruby/gems/1.8/gems/activesupport-2.3.2/lib/
active_support/core_ext/module/aliasing.rb:33:in `alias_method':
undefined method `name=' for class `Thing'

Seems like model doesn't know about its attributes at this point.
Even if I add my aliasing code after the class:
class Thing < ActiveRecord::Base
end
Thing.class_eval <<-eos
  def name_with_upcase=(r)
    self.name_without_upcase=(r.upcase)
  end
  alias_method_chain "name=", :upcase
eos

I get the same error.
But if I add a simple
puts Thing.new
between the class and the eval part, it works.

Any ideas how I can force the model to load it's attributes earlier?

Ok, found a solution: (I didn't know about write_attribute)
This works:
def name=(str)
  str.upcase! unless str.nil?
  write_attribute(:name, str)
end