process_conditions_for_preload

# File activerecord/lib/active_record/association_preload.rb, line 390
      def process_conditions_for_preload(conditions, klass = self)
        sanitized = klass.send(:sanitize_sql, conditions)

        if sanitized =~ /\#\{.*\}/
          ActiveSupport::Deprecation.warn(
            'String-based interpolation of association conditions is deprecated. Please use a ' \
            'proc instead. So, for example, has_many :older_friends, :conditions => \'age > #{age}\' ' \
            'should be changed to has_many :older_friends, :conditions => proc { "age > #{age}" }.'
          )
          instance_eval("%@#{sanitized.gsub('@', '\@')}@", __FILE__, __LINE__)
        elsif conditions.respond_to?(:to_proc)
          klass.send(:sanitize_sql, instance_eval(&conditions))
        else
          sanitized
        end
      end