use define_method to define class method

environment.rb

# via: http://stackoverflow.com/questions/752717/how-do-i-use-define-method-to-create-class-methods

class Environment
  def self.current
    ENV['APP_ENV'] ||= 'development'
  end
  
  %w(development product test).each do |environment|
    (class << self; self; end).instance_eval do
      define_method "#{environment}?" do
        self.current.to_s == environment.to_s
      end
    end
  end
end