happy.rb

#!/usr/bin/ruby -w

def ensure_data_file
  unless defined? DATA
    const_set(:DATA, File.open($PROGRAM_NAME, 'r+'))
    DATA.seek 0, IO::SEEK_END
    DATA.puts
    DATA.puts('__END__')
  end
  DATA
end

module AaronsIOMeow
  def reopen io_or_path = self.path, mode = 'r+'
    pos = self.pos
    new_data = super
    new_data.seek pos
    new_data
  end

  def db default = {}
    reopen
    start_position = self.pos

    db = Marshal.load(read) rescue default

    seek start_position

    yield db

    write Marshal.dump(db)
    truncate pos
  end
end

ensure_data_file
DATA.extend(AaronsIOMeow)

DATA.db(Hash.new 0) do |db|
  db[:key] += 1

  p db
end