Ruby：在方法内部调用的“ gets”方法将保存Nil而不是Input

Question

好的，这是在终端上运行的Dungeon Text Adventure项目中的。

当用户说他想“向北”时，它将拆分字符串：第一个单词检查方法，第二个单词检查参数。 那在其他地方发生，我复制粘贴了两种方法，这给了我以下问题：

当它调用go（north）并且north不是有效的连接时，它显示选项并再次询问用户方向，由于某种原因，用户在此刻输入的输入被存储为Nil。

为什么？？ 我也尝试过STDIN.gets.chomp.downcase！ 并且具有相同的零结果

这是代码：

    def find_room_in_direction(direction)

##-> if room connects with other on that direction, returns connection

        if find_room_in_dungeon(@player.location).connections.include?(direction.to_sym)
            return find_room_in_dungeon(@player.location).connections[direction.to_sym]

##-> if direction connection is not found, 
##-> show possible connections & return trigger to ask again inside go()

         elsif !find_room_in_dungeon(@player.location).connections.include?(direction.to_sym)
             puts "I don't see any #{direction}..."
             puts "This room only connects #{(find_room_in_dungeon(@player.location)).connections.keys.join(', ')}"
             puts "Where should we go?"

             return :redo
         end
         end


    def go(direction)

        current_direction = @player.location
        new_direction = find_room_in_direction(direction)

##-> if REDO trigger received, ask for new direction & try again

        if new_direction == :redo
            puts "REDOING DIRECTION"

    ##-> HERE IS THE PROBLEM:
    ##-> this does ask for input

            new_direction = gets.chomp.downcase!

##-> but it saves Nil instead of the input, so that puts shows ''

            puts "#{new_direction}"

##-> so this call trows an error: cant call method to Nil

            new_direction = find_room_in_direction(new_direction)

##-> if user entered valid direction from start, the following would run 

        elsif new_direction != :redo && current_direction != new_direction
            @player.location = new_direction
            puts "You go #{direction},"
            puts "and enter #{show_current_description}"
        end
        end

有什么建议么？ 谢谢！

Answer 1

您正在使用downcase! 而不是downcase 。 downcase! 就地更改字符串，如果没有更改（此处正在发生），则返回nil。

str = "teSt"
puts str.downcase # test
puts str # teSt
str.downcase! 
puts str # test

请参阅文档以了解downcase!

Answer 2

只是砰砰地一声。 至于小写，有两种变体-chomp和chomp！