在 programming ruby 书中介绍，为了保证模块中的实例变量具有唯一的名字，可以使用模块一级的散列表，以当前对象的 ID 作为索引，来保存实例的数据
module Test
State = {}
def state=(value)
State[object_id] = value
end
def state
State[object_id]
end
end
请问下模块一级的散列表，开头为大写，还有人具体讲解下模块一级的散列表的含义啊
简单试了下 感觉在 Module 中用大写字母的 Constant 就是为了想全局变量一样的共享吧。。
➜ 0 ~/tmp/test-project irb
1.9.3p429 :001 > module Test
1.9.3p429 :002?>
1.9.3p429 :003 > State = {}
1.9.3p429 :004?>
1.9.3p429 :005 > def state=(value)
1.9.3p429 :006?>
1.9.3p429 :007 > State[object_id] = value
1.9.3p429 :008?>
1.9.3p429 :009 > end
1.9.3p429 :010?>
1.9.3p429 :011 > def state
1.9.3p429 :012?>
1.9.3p429 :013 > State[object_id]
1.9.3p429 :014?>
1.9.3p429 :015 > end
1.9.3p429 :016?>
1.9.3p429 :017 > end
=> nil
1.9.3p429 :018 > class A; include Test; end
=> A
1.9.3p429 :019 > A::State
=> {}
1.9.3p429 :020 > a = A.new
=> #<A:0x007f929b016848>
1.9.3p429 :021 > a.state = 1
=> 1
1.9.3p429 :022 > a.state
=> 1
1.9.3p429 :023 > A::State
=> {70133821256740=>1}
1.9.3p429 :024 > Test::State
=> {70133821256740=>1}
1.9.3p429 :025 > class B; include Test; end
=> B
1.9.3p429 :026 > b = B.new
=> #<B:0x007f92990f6008>
1.9.3p429 :027 > b.state
=> nil
1.9.3p429 :028 > b.state = 2
=> 2
1.9.3p429 :029 > b.state
=> 2
1.9.3p429 :030 > b2 = B.new
=> #<B:0x007f9299061d40>
1.9.3p429 :031 > b2.state
=> nil
1.9.3p429 :032 > b2.state = 3
=> 3
1.9.3p429 :033 > b2.state
=> 3
1.9.3p429 :034 > Test::State
=> {70133821256740=>1, 70133804937220=>2, 70133804633760=>3}