understand self for attr_accessor class method

Question

class Test
  class << self
    attr_accessor :some

    def set_some
      puts self.inspect
      some = 'some_data'
    end
    def get_some
      puts self.inspect
      some
    end
  end
end

Test.set_some => Test
puts Test.get_some.inspect => Test nil

Here above I could find self as Test itself but not returning the some_data as output.

But while I modified in following way it returns expected output

class Test
  class << self
    attr_accessor :some

    def set_some
      puts self.inspect
      self.some = 'some_data'
    end
    def get_some
      puts self.inspect
      self.some
    end
  end
end

Test.set_some => Test
puts Test.get_some.inspect => Test some_data

What is the differences?

EDIT

Now in the first example if I set as get some method as

Test.some = 'new_data'
puts Test.some.inspect #=> new_data
Test.set_some
puts Test.get_some.inspect => new_data

Now it made me much more confused.

Answer 1

some = :foo makes ruby think it should create a new local variable with name some. If you want to call some=(), you have to use an explicit reciever - as in self.some = :foo. I once lost a bet on that... :-/