Question

class Curious
  def calculation
    def calculation
      @retrieved_value
    end
    @retrieved_value = #some kind of intensive process
  end
end

Doing the above, the outer method will be run the first time and the inner method will provide the value subsequent times. What’s the advantage or disadvantage of doing that over a single non-nested method that just does @retrieved_value ||= #some kind of intensive process?

Answer 1

You’re redefining the calculation method for the Curious class. This will affect other instances:

a = Curious.new
a.calculation # calls "outer" method, this sets @retrieved_value
a.calculation # calls "inner" method

b = Curious.new
b.calculation # calls "inner" method, @retrieved_value not set