How can I properly chain custom methods in Ruby?

Question

I am trying to do a chaining method for the following two methods. After running this code, I kept getting the following output:

#

        

Answer 1

Are you trying to do something like this?

class SimpleMath
  def initialize
    @result = 0
  end

  #1 add function
  def add(val)
    @result += val
    self
  end

  #2 Subtract function
  def subtract(val)
    @result -= val
    self
  end

  def to_s
    @result
  end
end

newNumber = SimpleMath.new
p newNumber.add(2).add(2).subtract(1)

For any number of arguments

class SimpleMath
  def initialize
    @result = 0
  end

  #1 add function
  def add(*val)
    @result += val.inject(&:+)
    self
  end

  #2 Subtract function
  def subtract(*val)
    @result -= val.inject(&:+)
    self
  end

  def to_s
    @result
  end
end

newNumber = SimpleMath.new
p newNumber.add(1, 1).add(1, 1, 1, 1).subtract(1)