Question

我试图让代码打印一个类的名称，然后在同一行上问候。例如：

(DriveThru): Hi, welcome to Starbucks! What can I get started for you?

这是我的代码：

module Order
  def order_drink
    "(#{self.class.name}): #{self.greeting}"
  end
end

class Lobby
  include Order
  attr_reader :name
  def initialize(name)
    @name = name
  end
  def greeting
    puts "Hi, welcome to Starbucks! How are you doing today #{self.name}?"
  end
end

class DriveThru
  include Order
  attr_reader :name
  def initialize(name)
    @name = name
  end
  def greeting
    puts "Hi, welcome to Starbucks! What can I get started for you #{self.name}?"
  end
end

dt = DriveThru.new("Tom")
lb = Lobby.new("Jessica")

puts dt.order_drink
puts lb.order_drink

当我运行代码时，它首先打印问候语，换行符，然后打印出类名：

"Hi, welcome to Starbucks! What can I get started for you?"
(DriveThru):

我做错了什么？

Answer 1

您的greeting函数正在执行puts语句。由于Ruby（和大多数其他编程语言）的工作方式，order_drink方法将在返回自己的值之前首先评估greeting方法的内容（调用puts语句）。

在每个puts函数的开头删除greeting，例如：

class Lobby
  include Order
  attr_reader :name
  def initialize(name)
    @name = name
  end
  def greeting
    "Hi, welcome to Starbucks! How are you doing today #{self.name}?"
  end
end

这将导致您的脚本输出以下内容：

(DriveThru): Hi, welcome to Starbucks! What can I get started for you Tom?
(Lobby): Hi, welcome to Starbucks! How are you doing today Jessica?

也就是说，最好为greeting属性添加attr_reader，并在initialize方法（也称为构造函数）中设置其值，如下所示：

class Lobby
  include Order
  attr_reader :name, :greeting
  def initialize(name)
    @name = name
    @greeting = "Hi, welcome to Starbucks! How are you doing today #{name}?"
  end
end

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