gistfile1.rb

# <rbriggs> is there any way to put conditions with regards to the source object in 
#           a has_many?  for example, I want so say foo.bars and have the bars 
#           association look for bars with an updated_at <= foo.updated_at (note: I 
#           know this can be done with a named_scope in bars.class - but I need this 
#           to be used in as a source association in a :through)

class Foo < ActiveRecord::Base
  has_many :bars
  def bars_before_me
    bars.updated_before(self.updated_at)
  end
end

class Bar < ActiveRecord::Base
  belongs_to :bar
  named_scope :updated_before lambda { |t| :conditions => ["updated_at < ?" t] }
end