之前有看过《ruby设计模式》，不过渐渐的都忘记了。现在买了一个大话设计模式，看起来不是那么枯燥，顺便将代码用ruby实现了一下。

简单工厂模式：

# -*- encoding: utf-8 -*- #运算类 class Operation attr_accessor :number_a,:number_b def initialize(number_a = nil, number_b = nil) @number_a = number_a @number_b = number_b end def result 0 end end #加法类 class OperationAdd < Operation def result number_a + number_b end end #减法类 class OperationSub < Operation def result number_a - number_b end end #乘法类 class OperationMul < Operation def result number_a * number_b end end #除法类 class OperationDiv < Operation def result raise '除数不能为0' if number_b == 0 number_a / number_b end end #工厂类 class OperationFactory def self.create_operate(operate) case operate when '+' OperationAdd.new() when '-' OperationSub.new() when '*' OperationMul.new() when '/' OperationDiv.new() end end end oper = OperationFactory.create_operate('/') oper.number_a = 1 oper.number_b = 2 p oper.result

这样写的好处是降低耦合。

比如增加一个开根号运算的时候，只需要在工厂类中添加一个分支，并新建一个开根号类，不会去动到其他的类。

工厂方法模式：

# -*- encoding: utf-8 -*- #运算类 class Operation attr_accessor :number_a,:number_b def initialize(number_a = nil, number_b = nil) @number_a = number_a @number_b = number_b end def result 0 end end #加法类 class OperationAdd < Operation def result number_a + number_b end end #减法类 class OperationSub < Operation def result number_a - number_b end end #乘法类 class OperationMul < Operation def result number_a * number_b end end #除法类 class OperationDiv < Operation def result raise '除数不能为0' if number_b == 0 number_a / number_b end end module FactoryModule def create_operation end end #加法工厂 class AddFactory include FactoryModule def create_operation OperationAdd.new end end #减法工厂 class SubFactory include FactoryModule def create_operation OperationSub.new end end #乘法工厂 class MulFactory include FactoryModule def create_operation OperationMul.new end end #除法工厂 class DivFactory include FactoryModule def create_operation OperationDiv.new end end factory = AddFactory.new oper = factory.create_operation oper.number_a = 1 oper.number_b = 2 p oper.result

相比于简单工厂模式，这里的变化是移除了工厂类，取而代之的是具体的运算工厂，分别是加法工厂、减法工厂、乘法工厂和除法工厂。