静态变量与本征类变量相比，Ruby有什么区别？

Question

I guess I'm asking for the difference between @store and @@store in the following:

class Test
  @@store = 9 
  class << self
    def set_store(v)
      @store = v
    end
    def store
      @store
    end
    def sstore
      @@store
    end
  end
end

Test.set_store 8
p Test.store # 8 
p Test.sstore # 9

a = Test.new

p a.class.store # 8
p a.class.sstore # 9

Where are static variables attached to if not the eigenclass? Are the two effectively the same in terms of interaction?

Answer 1

They are both class variables but in an instance you can access only @@store variable.

Mind that class variables are not thread safe in Ruby, so use Mutex if you plan to use varaible as a Hash.

Using class instance variable for mutex in Ruby