如何更改Ruby类变量值

我是Ruby新手，我想做的是

class WS< ActiveRecord::Base
  @@SequenceNumber = 0

  def self.oper1
    @@SequenceNumber = 2
  end

  def self.oper2
   @@SequenceNumber += 1 
   puts @@SequenceNumber.to_s
  end

  def self.oper3
   puts @@SequenceNumber.to_s
  end
end

我得到以下输出：

3
2

为什么我的@SequenceNumber+=1不能工作？我做错了什么

---

谢谢。

这是在预期的：

效果很好：

class WS
  @@sequence_number = 0

  def self.oper1
    @@sequence_number = 2
  end

  def self.oper2
   puts @@sequence_number += 1
  end

  def self.oper3
   puts @@sequence_number
  end
end

WS.oper3
# 0

WS.oper1
WS.oper2
# 3

WS.oper3
# 3

---

[注意：我冒昧地对您的代码进行了一点Rubyfying。]

也许您应该将这些内容全部输入出来，因为这很难阅读。

class WS
  @@sequence_number = 0

  def self.oper1
    @@sequence_number = 2
  end

  def self.oper2
   puts @@sequence_number += 1
  end

  def self.oper3
   puts @@sequence_number
  end
end

WS.oper3
# 0

WS.oper1
WS.oper2
# 3

WS.oper3
# 3