Why initialize instance variables from self.extended to base.class_eval?

If you read the Rails source, you will see

In ActiveSupport Autoload, click

The following code was found:

def self.extended(base)#:nodoc:
      base.class_evaldo
        @_autoloads={}
        @_under_path=nil
        @_at_path=nil
        @_eager_autoload=false
      end
end

for the class when extended

I'm defining class instance variables.

Why do I not use class variables?

Unlike class instance variables,
For class variables,
because the inheritance destination can reference the parent variable. I think it will work the same way as the above code.

ruby-on-rails ruby

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