Ruby Set类：集合的相等性

可以使用Date对象来演示其本质,其中包含不同Date对象但具有相同日期的集合比较相等：

require 'set'
d1 = Date.today              # => Thu,30 Sep 2010
puts d1.object_id            # => 2211539680
d2 = Date.today + 1          # => Fri,01 Oct 2010
puts d2.object_id            # => 2211522320
set1 = Set.new([d1,d2])

d11 = Date.today             # => Thu,30 Sep 2010
puts d11.object_id           # => 2211489080
d12 = Date.today + 1         # => Fri,01 Oct 2010
puts d12.object_id           # => 2211469380
set2 = Set.new([d12,d11])

set1 == set2                 # => true

但是使用我自己的对象,我在哪里编写了eql？方法只比较某些属性,我无法让它工作.

class IpDet

    attr_reader :ip,:gateway

    def initialize(ip,gateway,netmask,reverse)
        @ip = ip
        @gateway = gateway
        @netmask = netmask
        @reverse = reverse
    end

    def eql?(other)
        if @ip = other.ip && @gateway == other.gateway
            return true
        else
            return false
        end
    end
end



ipdet1 = IpDet.new(123456,123457,123458,'example.com')
ipdet2 = IpDet.new(234567,2345699,'nil')

ipdet11 = IpDet.new(123456,777777,'other_domain.com')
ipdet12 = IpDet.new(234567,'example.com')

puts "ipdet1 is equal to ipdet11: #{ipdet1.eql?(ipdet11)}"
puts "ipdet2 is equal to ipdet12: #{ipdet2.eql?(ipdet12)}"


set1 = Set.new([ipdet1,ipdet2])
set2 = Set.new([ipdet11,ipdet12])

puts "set 1 is equal to set2: #{set1 == set2}"

我从上面得到的输出是：

ipdet1 is equal to ipdet11: true
ipdet2 is equal to ipdet12: true
set 1 is equal to set2: false

任何人的想法？