我要评论之前有看过《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。
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