无法访问在我的 ruby​​ 函数之外定义的数组

Question

如何访问在函数外部定义的数组？我试过添加$coins.length，因为我在某处读过全局变量——它没有用。我在外面定义数组的原因是因为下面还有其他函数会将新项目推送到同一个数组中。

coins = []

def start

    puts "It's a sunny day. It's warm and you feel great."
    puts "You've picked up your son from creche. He's in a good mood and you've got home no problem."
    puts "This is when troubles start, and you know it."
    puts "You go out of the elevator and before you reach the door... 'give me the keeys'!"
    puts "Do you give him the keys? (Y/N)"
    print "> "


    while keys = gets.chomp.downcase
        case keys
        when "y"
            puts "you are in, good job. And you get a coin"
            coins.push("1")
            puts "you now have #{coins.length} coins"
            room
        when "n"
            cry("I wanted to dooooooo iiiiiiiit!")
        else    
            again
        end
    end
end

Answer 1

Ruby 是一种面向对象的语言。更重要的是，Ruby 以“一切皆对象”的座右铭出现在现场。 Ruby 中的偶数和（原文如此！）nil 是对象：

▶ 42.class
#⇒ Fixnum < Integer
▶ nil.__id__
#⇒ 8

因此，您应该将对象用于比单行稍微复杂的任何事情。对象有很多开箱即用的优点：实例变量、生命周期等。

class Game
  def initialize
    @coins = []
  end

  def add_coin(value)
    @coins << value
  end

  def coins
    @coins
  end

  def amount
    @coins.size
  end
end

现在你可以在这个类的实例中创建，当它还活着时，它会保存@coins的值：

game = Game.new
game.add_coin("1")
puts game.coins
#⇒ ["1"]
puts game.amount
#⇒ 1
game.add_coin("1")
game.add_coin("2")
puts game.coins
#⇒ ["1", "1", "2"]
puts game.amount
#⇒ 3

Answer 2

不要定义全局变量，而是尝试定义一个可以在任何地方使用的方法，例如：

def coins
  @coins ||= []
end

def start

    puts "It's a sunny day. It's warm and you feel great."
    puts "You've picked up your son from creche. He's in a good mood and you've got home no problem."
    puts "This is when troubles start, and you know it."
    puts "You go out of the elevator and before you reach the door... 'give me the keeys'!"
    puts "Do you give him the keys? (Y/N)"
    print "> "


    while keys = gets.chomp.downcase
        case keys
        when "y"
            puts "you are in, good job. And you get a coin"
            coins.push("1")
            puts "you now have #{coins.length} coins"
            room
        when "n"
            cry("I wanted to dooooooo iiiiiiiit!")
        else    
            again
        end
    end
end

这样，该方法将不是全局的，其他方法也可以在文件中访问该方法（coins）。