I know ruby treat an object as false whenever it is nil or false.
However, I wonder if there are any other ways to change this behavior.

For example, I define a class called AreYouOk.
class AreYouOk
      def initialize(ok)
            @ok = ok
      end
end

x = AreYouOk.new(false)
puts "you are ok" if x

Since x is not nil, ruby prints " you are ok".
However, I want ruby to make the decision based on the @ok instance
variable. Are there any ways to do that?

I know that there is a method called __bool__ in Python. You can
define your __bool__ method in your class. The truth value of an
object is based on the return value of __bool__. Does ruby provide
similar mechanism?