RUBY: how to resolve circular dependency in constant definitions?

class A
  X = 9
  Y = B::X
end

class B
  X = 8
  Y = A::X
end

I have two classes each defining some constants but requiring constants from the other as shown above but this gives开发者_运维百科 me an error:

circular.rb:7:in <class:A>': uninitialized constant A::B (NameError) from circular.rb:5:in'

Is there any way to resolve the error ?

Thanks.

It works if you split the definition of A into two parts:

class A
  X = 9
end

class B
  X = 8
  Y = A::X
end

class A
  Y = B::X
end