ROR中的开/闭原则

ROR中的开/闭原则

软件元素(类、模块、函数等等)应该对扩展开放，但对修改关闭。编写良好的类不应该为了集成新特性(比如添加新的属性地址)而重写：

class OrderReport
  def initialize(customer:, total:)
    @customer = customer
    @total = total
  end

  def invoice
    puts "Invoice"
    puts @customer
    puts @total
  end

  def bill_of_lading
     puts "BOL"
     puts @customer
     puts "Shipping Label..."
  end
end

order = OrderReport.new(customer: "Google", total: 100)
order.invoice
order.bill_of_lading 

在原类上新增属性或者方法（破坏了closed原则）

class OrderReport
  def initialize(customer:, total:, address:)
    @customer = customer
    @total = total
    @address = address
  end

  def invoice
    puts "Invoice"
    puts @customer
    puts @total
  end

  def bill_of_lading
    puts "BOL"
    puts @customer
    puts "Shipping Label..."
    puts @address
  end
end

order = OrderReport.new(customer: "Google",
                         total: 100,
                         address: "123 Any Street")
order.invoice
order.bill_of_lading

较好的方式如下

class OrderReport
    def initialize(customer:, total:)
        @customer = customer
        @total = total
    end
end

class Invoice < OrderReport
    def print_out
        puts "Invoice"
        puts "Customer: #{@customer}" 
        puts "Total:  #{@total} "
    end
end

class BillOFLading < OrderReport
    def initialize(address:, **arguments)
        super(**arguments)
        @address = address
    end

    def print_out
        puts "BOL"
        puts "Customer: #{@customer}"
        print "Shipping Address: #{@address}"
    end
end

invioce = Invoice.new(customer: "Baidu", total: 200)
bill_of_lading = BillOFLading.new(customer: "Yahoo",
                         total: 100, 
                         address: " 123 Any Street")

invioce.print_out
puts 
bill_of_lading.print_out

这种重构有很多好处:
它遵循开/关原则，因为现在当我们为发票或提单构建新特性时，我们不必触及OrderReport类。因此，我们可以说父类是关闭的。
此外，由于我们拆分了这两个组件，所以无论何时创建发票，我们都不必传递不必要的address元素。这将删除不需要的代码，这可能会在以后导致混淆。
最后，我们的程序不仅遵循开/闭原则，同时也遵循SRP

Question

：如果您运行这段代码，您将看到它仍然具有与以前相同的结果，现在我们的代码可扩展性更强了，那么我们敢说，我们已经遵守SOLID原则了吗?