將紅寶石哈希傳入類

Question

我遇到了一個研究演練問題，我無法弄清楚。 下面是練習的鏈接。 https://learnrubythehardway.org/book/ex40.html

以下是我的工作。在學習鑽2，我通過了變量，它的工作。 但是，在學習演習3中，我弄壞了我的代碼。我意識到我沒有傳遞變量，而是散列。因爲我的課程有兩個參數，所以我無法弄清楚如何將字典作爲2個參數傳遞。

class Song 

    def initialize(lyrics, singer) 
    @lyrics = lyrics 
    @singer = singer 
    end 

    def sing_along() 
    @lyrics.each {|line| puts line} 
    end 

    def singer_name() 
    puts "The song is composed by #{@singer}" 
    end 

    def line_reader(lineNum) 
    line = @lyrics[lineNum-1] 
    puts "The lyrics line #{lineNum} is \"#{line}\"." 
    end 

end 

# The lyrics are arrays, so they have [] brackets 
practiceSing = Song.new(["This is line 1", 
       "This is line 2", 
       "This is line 3"],"PracticeBand") 

practiceSing.sing_along() 
practiceSing.singer_name() 
practiceSing.line_reader(3) 

puts "." * 20 
puts "\n" 

# Variable for passing. Working on dictionary to pass the singer value. 
lovingThis = {["Don't know if I'm right", 
       "but let's see if this works", 
       "I hope it does"] => 'TestingBand'} 

# Everything after this line is somewhat bugged 
# Because I was using a variable as an argument 
# I couldn't figure out how to use dictionary or function to work with 
this 

practiceVariable = Song.new(lovingThis,lovingThis) 

practiceVariable.sing_along() 
practiceVariable.singer_name() 
practiceVariable.line_reader(3) 

這是Output。它應該做的是返回歌手/樂隊，並返回請求的歌詞行。

我是新來的編碼，請告知如何將哈希值傳入類？ 如何將這個散列傳遞給Song.new（）並將其讀爲2個參數？

Answer 1

你可以通過哈希類的構造函數以同樣的方式，因爲我們傳遞任何其他變量，但你需要改變你的構造函數定義，將可變數量的參數，即def initialize(*args)

class Song 
    def initialize(*args) 
    if args[0].instance_of? Hash 
     @lyrics = args[0].keys.first 
     @singer = args[0].values.first 
    else 
     @lyrics = args[0] 
     @singer = args[1] 
    end 
    end 

    def sing_along() 
    @lyrics.each {|line| puts line} 
    end 

    def singer_name() 
    puts "The song is composed by #{@singer}" 
    end 

    def line_reader(lineNum) 
    line = @lyrics[lineNum-1] 
    puts "The lyrics line #{lineNum} is \"#{line}\"." 
    end 
end 

# The lyrics are arrays, so they have [] brackets 
practiceSing = Song.new(["This is line 1", 
       "This is line 2", 
       "This is line 3"],"PracticeBand") 

practiceSing.sing_along() 
practiceSing.singer_name() 
practiceSing.line_reader(3) 

puts "." * 20 
puts "\n" 

# Variable for passing. Working on dictionary to pass the singer value. 
lovingThis = {["Don't know if I'm right", 
       "but let's see if this works", 
       "I hope it does"] => 'TestingBand'} 

practiceVariable = Song.new(lovingThis) 

practiceVariable.sing_along() 
practiceVariable.singer_name() 
practiceVariable.line_reader(3)