ruby - 为什么不使用 `@messages`？

Question

以下来自The Rspec Book .我想知道为什么 messages << message在def puts不是 @messages << message .我明白 ||= []是内存，我也明白@messages是实例变量。那么，是否应该在同一个类(class)中使用呢？还是打错了？

class Output
  def messages
    @messages ||= []
  end

  def puts(message)
    messages << message
  end
end

def output
  @output ||= Output.new
end

Given /^I am not yet playing$/ do
end

When /^I start a new game$/ do
  game = Codebreaker::Game.new(output)
  game.start
end

Then /^I should see "([^"]*)"$/ do |message|
  output.messages.should include(message)
end

Answer 1

我认为您混淆了 @messages 变量和 messages 方法

class Output
  def messages
    @messages ||= []
  end

  def puts(message)
    messages << message #=> here `messages` refer to the method above
  end
end

这是一个简单的例子

class Output
  def m
    @messages ||= []
  end

  def puts(message)
    m << message #=> method `m`
  end
end

v = Output.new
v.puts "blah"
v.m #=> ["blah"]

示例 2(为了更清楚)

class Output
  def m
    @messages ||= []
  end

  def puts(message)
    m << message #=> here `m` refer to the method above
  end

  def show_at_messages_variable
    @messages
  end
end

v = Output.new
v.puts "blah"
v.show_at_messages_variable #=> ["blah"]