Question

我从昨天开始学习Ruby。以下是我的疑问：

class MegaGreeter
      attr_accessor :names

      def intialize(names="World!")
        @names = names
      end

      def say_test
        if @names.nil?
          puts "nil test..."
        end
      end  

    end


    megaGreeter = MegaGreeter.new
    megaGreeter.say_test // Here showing ouput as "nil test..."

起初我只是assuming 'nil' almost like 'null' in java。但在上述情况下，我的假设似乎是错误的。

我不明白为什么在if @names.nil returning as TRUE以上？，因为@names will have a value "World!"所以，@ names如何视为null？

我已经搜索了“nil”，但我真的没有清楚地了解它。

Answer 1

你有一个错字。 #intialize应为initialize。

见，

class MegaGreeter
  attr_accessor :names

  def initialize(names = "World!")
    @names = names
  end

  def say_test
    if @names.nil?
      puts "nil test..."
    else
      puts "@names is not holding nil"
    end
  end  
end

megaGreeter = MegaGreeter.new
megaGreeter.say_test # => @names is not holding nil
megaGreeter = MegaGreeter.new(nil)
megaGreeter.say_test # => nil test...

ruby nil让我困惑

1 个答案: