1-setup.bash

cd /tmp
brew update
brew upgrade ruby-build
rbenv install 2.0.0-p0
rbenv shell 2.0.0-p0
curl -fsSL curl.haxx.se/ca/cacert.pem -o "$(ruby -ropenssl -e 'puts OpenSSL::X509::DEFAULT_CERT_FILE')"
gem install bundler --pre # Successfully installed bundler-1.3.0.pre.8
gem install rails # Successfully installed rails-3.2.12
rails new test-app
cd test-app
curl -s https://gist.github.com/timblair/5029591/raw/2-tableless.rb -o app/models/tableless.rb

2-tableless.rb

# From http://stackoverflow.com/a/938786/207828
class Tableless < ActiveRecord::Base
  def self.columns
    @columns ||= [];
  end

  def self.column(name, sql_type = nil, default = nil, null = true)
    columns << ActiveRecord::ConnectionAdapters::Column.new(name.to_s, default, sql_type.to_s, null)
  end

  # Override the save method to prevent exceptions.
  def save(validate = true)
    validate ? valid? : true
  end
end

3-irb.rb

# bundle exec rails console
Loading development environment (Rails 3.2.12)
>> Tableless.new.dup
NoMethodError: private method `initialize_dup' called for #<Tableless >