SOLID in Rails - Interface Segregation Principle

Many client specific interfaces are better than one general purpose interface.

We want to show or create Fee. It's the same method but with additional options - save or not, so we pass params true or false

	class FeeCalculator
	def calculate(product, user, vat, save_result)
	# calculation
	if save_result
	# storing result into db
	end
	end
	end
	class ProductController
	def show
	@fee = FeeCalculator.new.calculate(product, user, vat, false)
	end
	end
	class OrderController
	def create
	@fee = FeeCalculator.new.calculate(product, user, vat, true)
	end
	end

view raw Solid-I01.rb hosted with ❤ by GitHub

But good way is divide this one action to different actions

	class FeeCalculator
	def calculate(product, user, vat)
	# calculation
	end
	def save(fee)
	# storing result into db
	end
	end
	class OrderController
	def create
	fee = fee_calculator.calculate(product, user, vat)
	fee_calculator.save(fee)
	end
	private
	def fee_calculator
	FeeCalculator.new
	end
	end
	class ProductController
	def show
	@fee = FeeCalculator.new.calculate(product, user, vat)
	end
	end

view raw Solid-I02.rb hosted with ❤ by GitHub

http://rubyblog.pro/