# File lib/active_record/base.rb, line 828
      def with_scope(method_scoping = {}, action = :merge, &block)
        method_scoping = method_scoping.method_scoping if method_scoping.respond_to?(:method_scoping)

        # Dup first and second level of hash (method and params).
        method_scoping = method_scoping.inject({}) do |hash, (method, params)|
          hash[method] = (params == true) ? params : params.dup
          hash
        end

        method_scoping.assert_valid_keys([ :find, :create ])

        if f = method_scoping[:find]
          f.assert_valid_keys([ :conditions, :joins, :select, :include, :from, :offset, :limit, :readonly ])
          f[:readonly] = true if !f[:joins].blank? && !f.has_key?(:readonly)
        end

        # Merge scopings
        if action == :merge && current_scoped_methods
          method_scoping = current_scoped_methods.inject(method_scoping) do |hash, (method, params)|
            case hash[method]
              when Hash
                if method == :find
                  (hash[method].keys + params.keys).uniq.each do |key|
                    merge = hash[method][key] && params[key] # merge if both scopes have the same key
                    if key == :conditions && merge
                      hash[method][key] = [params[key], hash[method][key]].collect{ |sql| "( %s )" % sanitize_sql(sql) }.join(" AND ")
                    elsif key == :include && merge
                      hash[method][key] = merge_includes(hash[method][key], params[key]).uniq
                    else
                      hash[method][key] = hash[method][key] || params[key]
                    end
                  end
                else
                  hash[method] = params.merge(hash[method])
                end
              else
                hash[method] = params
            end
            hash
          end
        end

        self.scoped_methods << method_scoping

        begin
          yield
        ensure
          self.scoped_methods.pop
        end
      end