Question

我不确定为什么我的代码不会通过相应的测试。每次我尝试代码时，都会报告以下错误：“rb：60：in <main>': undefined local variable or method track”for main：Object（NameError）。“如果不编辑测试，我该怎么办？谢谢！打开另一种方法......谢谢！强文

class Song
  attr_reader :song 
  def initialize(song, artist)
    @song = song
    @artist = artist
  end
  def play
   puts "#{@song}by #{@artist}"
  end
end

class Playlist
  def initialize(player_list)
    @player_list = player_list
  end

  def add(add_song)
      add_song.each do |song|
          @player_list << song
      end
  end

  def track_number
      @player_list.length 
  end

  def remove(remove_song)
      remove_song.each do |song|
          @player_list.delete(song)
      end
  end

  def includes?(from_list)
      i = 0
      from_list.each do |song|
          if @player_list.include?(song) 
                i+=1
          end
      end
      if i==from_list.length 
        true
      else 
         false
      end
   end

  def play_all
      @player_list.each do |song|
            song.play
      end
  end

  def display
      @player_list.each do |song|
          puts song.song 
      end
  end
end



 one_by_one = Song.new("One by One", "Sirenia")
 world_so_cold = Song.new("World So Cold", "Three Days Grace") 
 going_under = Song.new("Going Under", "Evanescence")

 my_playlist = Playlist.new(one_by_one, world_so_cold, going_under)

 lying_from_you = Song.new("Lying From You", "Linkin Park")
 angels = Song.new("Angels", "Within Temptation")

 my_playlist.add(lying_from_you, angels)
 p my_playlist.track_number == 5
 going_under.play
 my_playlist.remove(angels)
 p my_playlist.includes?(lying_from_you) == true
 my_playlist.play_all
 my_playlist.display

Answer 1

当你为PlayList调用“add”方法时，它会期待一首歌曲。但是，“add”方法试图调用.each（），它可以用于一组歌曲但不能用于单首歌曲。

在不更改测试代码的情况下，最佳解决方案是删除“添加”，“删除”和“包含”中的“.each”调用。 PlayList的方法。让他们每次添加，删除或检查一首歌。

用红宝石创建一个可调整的播放列表

1 个答案: