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。
# -*- 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。