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今天我们继续说一下

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实现领域驱动设计

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译文里面暴露的问题

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前面三个视频，我们提到了第①句

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存在的问题

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以及背后可能的思想根源

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那我们

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今天开始来看第②句

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第②句原文这个

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中译本译文这个

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首先，第一个问题

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并不存在遍历

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你看

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原文是这样

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译文是这样

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那我们来看一下

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原文

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它用词只用了navigate

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意思是导航

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它并没有用遍历

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如果它用遍历的话

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它应该用的什么

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traversal或者traverse

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类似这样的词

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意思是遍历

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遍历在计算机科学的特定场景里面

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它的意思就是

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访问所有的结点

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但是

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我们要知道

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在一个整体-部分结构的

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这样一个

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里面

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整体对象要履行责任的时候

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它并不需要遍历所有的部件

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也就是说

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一个对象

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在执行某个行为的时候

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并不一定涉及（当然，也可以涉及）

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所有直接或间接的

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部分对象

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比如说，这是类图

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A组合B

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B组合DE，A组合C

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对象图我们画出来是这样

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A对象，a1

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组合了一个b1、b2

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这两个都是B

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还组合两个C，也就是，a里面有两个b两个c

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b里面它自己也有自己内部结构了

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那当a

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执行某个操作

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或者说，它收到某个消息

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要执行某个操作的时候

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可能只会影响到

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只会把

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这个操作分解分配发给它的

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下面的某个部件

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比如说，发给b1

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b2可能就不会发给它

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同时可能发给c1

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c2可能不会发

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也可能只发给b

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c都不会发

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对不对

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就像我们订单里面有很多属性嘛

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有若干个订单项

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还有下单日期

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还有其他的一些

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包括配送地址什么之类的

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那很可能它现在收到一个消息说

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我要修改

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某个地址

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那可能影响的是地址这个属性而已

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其他的不影响，下单日期，不影响

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对不对

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或者说，我删除某个订单项

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我从订单里面删除某个订单项

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那只是影响到那个订单项

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其他订单项不受影响

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怎么可能要遍历呢

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不可能遍历的嘛

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对吧

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或者我们举最简单的例子

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类和属性，就知道了嘛

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一个类有很多个属性

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很多个操作

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那某个操作

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可能涉及到的只是其中

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某些属性

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这个操作可能涉及到的，可能是这里面

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某些属性

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也可能是重叠的

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它不会说

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执行一个操作

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所有的属性都要访问

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或者说都要修改

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那不会的了

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对不对

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所以呢，这个不是英文的

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翻译的问题，是我们在概念上

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就没有搞清楚

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不存在遍历的问题

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跟我们前面讲那个关联是一样的

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不是说，我英语不好

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用词用错了

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不是这个意思

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当然也有这方面因素

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但是呢

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关键点不在这里

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这是第（1）点

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第（2）点

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那我们再往外推

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你看，它说什么

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深度地递归遍历

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首先深度地，这是有的

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遍历是没有的，是导航

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对吧

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但这个递归是译者自己加上去的

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那为什么有这样的一个翻译

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背后可能会有什么样的

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思想的根源

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这个我们下次再说