Refactoring: Removing Tangled Control Coupling

payroll_calculator_step_0.rb

class PayrollCalculator
  def initialize(payroll, options = {})
    @payroll = payroll
    @skip_benefits = options[:skip_benefits]
    @skip_taxes = options[:skip_taxes]
    @skip_donations = options[:skip_donations]
  end

  def calculate
    if !@skip_benefits
      result = calculate_benefits(@payroll)
    end

    if !@skip_donations
      result = calculate_donations(@payroll, result)
    end

    if !@skip_taxes
      result = calculate_taxes(@payroll, result)
    end

    result
  end
end

payroll_calculator_step_1.rb

class PayrollCalculator
  def initialize(payroll, options = {})
    @payroll = payroll
    @skip_benefits = options[:skip_benefits]
    @skip_taxes = options[:skip_taxes]
    @skip_donations = options[:skip_donations]
  end

  def calculate
    if !@skip_benefits
      result = BenefitsCalculator.calculate(@payroll)
    end

    if !@skip_donations
      result = calculate_donations(@payroll, result)
    end

    if !@skip_taxes
      result = calculate_taxes(@payroll, result)
    end

    result
  end
end

class BenefitsCalculator
  def self.calculate(payroll)
    # The guts of the method formerly known
    # as PayrollCalculator#calculate_benefits
  end
end

payroll_calculator_step_2.rb

class PayrollCalculator
  def initialize(payroll, options = {})
    @payroll = payroll

    if options[:skip_benefits]
      @benefits_calculating_klass = NullCalculator
    else
      @benefits_calculating_klass = BenefitsCalculator
    end

    @skip_taxes = options[:skip_taxes]
    @skip_donations = options[:skip_donations]
  end

  def calculate
    result = @benefits_calculating_klass.calculate(@payroll)

    if !@skip_donations
      result = calculate_donations(@payroll, result)
    end

    if !@skip_taxes
      result = calculate_taxes(@payroll, result)
    end

    result
  end
end

class BenefitsCalculator
  def self.calculate(payroll)
    # The guts of the method formerly known
    # as PayrollCalculator#calculate_benefits
  end
end

class NullCalculator
  def self.calculator(payroll, result)
    result
  end
end

payroll_calculator_step_3.rb

class PayrollCalculator
  def initialize(
    payroll,
    benefits_calculating_klass: BenefitsCalculator,
    **options
  )
    @payroll = payroll

    @benefits_calculating_klass = benefits_calculating_klass

    @skip_taxes = options[:skip_taxes]
    @skip_donations = options[:skip_donations]
  end

  def calculate
    # (unchanged from previous snippet)
  end
end

payroll_calculator_step_4.rb

class PayrollCalculator
  def initialize(
    payroll,
    benefits_calculating_klass: BenefitsCalculator,
    tax_calculating_klass: TaxCalculator,
    donation_calculating_klass: DonationCalculator
  )
    @payroll = payroll
    @benefits_calculating_klass = benefits_calculating_klass
    @tax_calculating_klass = tax_calculating_klass
    @donation_calculating_klass = donation_calculating_klass
  end

  def calculate
    result = @benefits_calculating_klass.calculate(@payroll)

    result = @donation_calculating_klass.calculate(
      @payroll,
      result
    )

    @tax_calculating_klass.calculate(
      @payroll,
      result
    )
  end
end

print_address.rb

def print_address(include_zip_code)
  if include_zip_code
    street_1 + city + state + zip_code
  else
    street_1 + city + state
  end
end