POO em Ruby - Relacionado a thread https://t.me/rubybrasil/179048

oop.rb

module Calc
  module Outputs
    class InMemory
      attr_reader :history

      def initialize
        @history = []
      end

      def puts(value)
        @history << value
      end
    end

    class Stdout
      def puts(value)
        Kernel.puts(value)
      end
    end
  end

  class Operations
    def sum(a, b)
      a + b
    end

    def sub(a, b)
      a - b
    end
  end

  class Program
    def initialize(output, operations)
      @output = output
      @operations = operations
    end

    def sum(a, b)
      @output.puts @operations.sum(a, b)
    end
  end
end

output = Calc::Outputs::Stdout.new
operations = Calc::Operations.new

calc = Calc::Program.new(output, operations)
calc.sum(1, 1)

# raise "expect #{output.history.last} to be equal to 2" if output.history.last != 2