2nd_try_result.rb

ree-1.8.7-2011.03 :001 > GolfBall.without_dimples
NameError: undefined local variable or method `dimples' for #<Class:0xc0c0290>

golfball.rb

class GolfBall < ActiveRecord::Base

  has_many :dimples, :dependent => :destroy

  named_scope :without_dimples, :conditions => lambda {|g| g.dimples.size == 0}
end

golfball_2nd_try.rb

class GolfBall < ActiveRecord::Base

  has_many :dimples, :dependent => :destroy

  named_scope :without_dimples, :conditions => g.dimples.size == 0
end

result.rb

ree-1.8.7-2011.03 :001 > GolfBall.without_dimples
ActiveRecord::StatementInvalid: Mysql::Error: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '' at line 1: SELECT * FROM `golf_balls` WHERE (#<Proc:0x0c4f0950@/home/path/golf_ball.rb:27>)