module Status
  BAD  = 13
  GOOD = 24

  def self.to_str(status)
    for sym in self.constants
      if self.const_get(sym) == status
        return sym.to_s
      end
    end
  end

end


mystatus = Status::GOOD

puts Status::to_str(mystatus)

输出:

GOOD

也许最好的轻量级方法是

module MyConstants
  ABC = Class.new
  DEF = Class.new
  GHI = Class.new
end

这样，值就有了关联的名称，就像在Java/ c#中一样:

MyConstants::ABC
=> MyConstants::ABC

要获得所有的值，可以这样做

MyConstants.constants
=> [:ABC, :DEF, :GHI] 

如果你想要枚举的序号值，你可以这样做

MyConstants.constants.index :GHI
=> 2

另一种解决方案是使用OpenStruct。它非常简单明了。

https://ruby-doc.org/stdlib-2.3.1/libdoc/ostruct/rdoc/OpenStruct.html

例子:

# bar.rb
require 'ostruct' # not needed when using Rails

# by patching Array you have a simple way of creating a ENUM-style
class Array
   def to_enum(base=0)
      OpenStruct.new(map.with_index(base).to_h)
   end
end

class Bar

    MY_ENUM = OpenStruct.new(ONE: 1, TWO: 2, THREE: 3)
    MY_ENUM2 = %w[ONE TWO THREE].to_enum

    def use_enum (value)
        case value
        when MY_ENUM.ONE
            puts "Hello, this is ENUM 1"
        when MY_ENUM.TWO
            puts "Hello, this is ENUM 2"
        when MY_ENUM.THREE
            puts "Hello, this is ENUM 3"
        else
            puts "#{value} not found in ENUM"
        end
    end

end

# usage
foo = Bar.new    
foo.use_enum 1
foo.use_enum 2
foo.use_enum 9


# put this code in a file 'bar.rb', start IRB and type: load 'bar.rb'

有人走在前面，写了一个红宝石宝石叫Renum。它声称获得了最接近Java/ c#的行为。就我个人而言，我仍然在学习Ruby，当我想让一个特定的类包含一个静态枚举(可能是一个散列)时，我有点震惊，因为它不太容易通过谷歌找到。

如果你使用的是Rails 4.2或更高版本，你可以使用Rails枚举。

Rails现在默认有枚举，不需要包含任何宝石。

这与Java、c++的枚举非常相似(并且具有更多的特性)。

引用自http://edgeapi.rubyonrails.org/classes/ActiveRecord/Enum.html:

class Conversation < ActiveRecord::Base
  enum status: [ :active, :archived ]
end

# conversation.update! status: 0
conversation.active!
conversation.active? # => true
conversation.status  # => "active"

# conversation.update! status: 1
conversation.archived!
conversation.archived? # => true
conversation.status    # => "archived"

# conversation.update! status: 1
conversation.status = "archived"

# conversation.update! status: nil
conversation.status = nil
conversation.status.nil? # => true
conversation.status      # => nil

我实现过这样的枚举

module EnumType

  def self.find_by_id id
    if id.instance_of? String
      id = id.to_i
    end 
    values.each do |type|
      if id == type.id
        return type
      end
    end
    nil
  end

  def self.values
    [@ENUM_1, @ENUM_2] 
  end

  class Enum
    attr_reader :id, :label

    def initialize id, label
      @id = id
      @label = label
    end
  end

  @ENUM_1 = Enum.new(1, "first")
  @ENUM_2 = Enum.new(2, "second")

end

然后很容易做操作

EnumType.ENUM_1.label

...

enum = EnumType.find_by_id 1

...

valueArray = EnumType.values