maxime$ rails console
[datamapper] Setting up the "development" environment:
[datamapper] Setting up :default repository: 'accounting_development' on postgres
Loading development environment (Rails 3.0.0.beta1)
irb(main):001:0> class Person
irb(main):002:1> end
=> nil
irb(main):003:0> Person.metaclass
NoMethodError: undefined method `metaclass' for Person:Class
	from (irb):3