I would like to define dynamic methods based on some options people give when instantiating it. So in their AR model, they'd do something like this:

acts_as_something :class_name => "CustomClass"

I'm trying to implement that like so:

module MyModule
  def self.included(base)

    as = Config.class_name.underscore
    foreign_key = "#{as}_id"

    # 1 - class eval, throws these errors
    # ~/test-project/helpers/form.rb:45: syntax error, unexpected $undefined
    #        @ ||= MyForm.new(
    #         ^
    # ~/test-project/helpers/form.rb:46: syntax error, unexpected ','
    #~/test-project/helpers/form.rb:48: syntax error, unexpected ')', 
    # expecting kEND    from ~/test-project/helpers.rb:12:in `include'

    base.class_eval <<-"end_eval", __FILE__, __LINE__
      attr_accessor :#{as}

      def #{as}
        @#{as} ||= MyForm.new(
          :id => self.#{foreign_key},
          :title => self.title
        )
        @#{as}
      end
    end_eval
  end
end

But it's throwing a bunch of errors I've printed in the comments. Am I using this incorrectly? What are some better ways I can define dynamic method names and dynamic names inside the method like this? I see people use this often instead of define_method (see these classes in resource_controller and couchrest toward the bottom). What I missing here?

Thanks for the help