gistfile1.rb

  yes_no_conditions_creator = lambda {|yes_or_no,field_name|
    if yes_or_no == 'yes'
      {:conditions => "books.#{field_name.to_s} = true"}
    elsif yes_or_no == 'no'
      {:conditions => "books.#{field_name.to_s} = false or books.#{field_name.to_s} is null"}
    else
      {}
    end
  }
  
  named_scope :by_period_assigned, lambda {|yes_or_no| yes_no_conditions_creator.call(yes_or_no, :period_assigned)}
  named_scope :by_priority_assigned, lambda {|yes_or_no| yes_no_conditions_creator.call(yes_or_no, :priority_assigned)}
  named_scope :by_is_technically_copied, lambda {|yes_or_no| yes_no_conditions_creator.call(yes_or_no, :is_technically_copied)}
  named_scope :by_verification_completed, lambda {|yes_or_no| yes_no_conditions_creator.call(yes_or_no, :verification_completed)}