Modifying old code adds the risk of breaking existing functionality.
修改旧有代码增添了破坏已有功能的风险。
One such example occurs when refactoring old code to help simplify it and make it more readable.
重构旧代码以进行简化并提高可读性就是这样一个例子。
Root cause was the old code that deployed past weekend could not handle TAB character correctly.
基本缘由是旧地代码，摆设啦曩昔周末不克不及处置统计表性格准确。
In this case, the underscore in line 105 was just some easy-to-fix detritus from 10-year-old code.
在这个例子中，105行的下划线只是一个有10年之久的老代码中一些容易修正的小毛病。
Rewriting old code simply to change its style may result in the introduction of costly yet avoidable defects.
在重写代码的时候简单粗暴地改变原有风格，会导致代价惨重的缺陷，而其实这些完全都是可以避免的。
So you generally work on an existing codebase, but yet it's easier to write all new code than it is to change old code.
所以，你通常基于现有的代码库进行工作，可是写全新的代码又比修改旧的代码容易得多。
Whether you need to double back and revisit some old code, write some more test cases, or even delay a deadline — do it.
不管是否需要你回顾还是重新查看一些旧代码，都要多写一些测试用例，甚至推迟截止日期也要这么做。
Reading your own old code, from a project you are not currently working on, can also be an enlightening experience.
读你自己的老代码，从非你当前工作的项目中，也将是有启发的经验。
You'd be surprised at how old code can be resurrected into a possible and better routine, or maybe even an entire product.
你也许会惊叹，旧代码也能复活成为一种更好的程序，甚至是一个完整的产品。
It's best to comment out the old code and add comments to the new code so it will be easier to track your modifications.
最好是注释掉旧代码并对新代码添加注释，这样可以更轻松地跟踪您的修改。
Whether you need to double back and revisit some old code, write some more test cases, or even delay a deadline — do it.
无论你是否需要后退两步复查一些老代码，写更多的测试用例，或者甚至是推迟一个截止期限——做下去。
Its old code had warned employees against such things as greasy or highly gelled hair or wearing flowers as accessories.
该公司的旧规定警告员工不要让头发看起来油腻腻的，或上太多发胶，也不要将花作为装饰物佩戴。
Because large portions of the Mac OS were still based on creaky old code, Apple decided that it had to start from scratch.
由于很大一部分的MacOS仍基于陈旧的代码，苹果公司决定另起炉灶、从头开始。
The new hybrid method combines the best of new and old code cracking methods for "fingerprinting" the genetic basis of life.
此新方法吸取了新老密码破译方法的长处以解读生命的遗传基础。
Similarly, messages created by your new code can be parsed by your old code: old binaries simply ignore the new field when parsing.
类似地，你的新代码创建的消息也能被你的老代码解析：老的二进制程序在解析的时候只是简单地将新字段忽略。
After you have done this you can safely refactor code and implement new features and be confident that your old code has not broken.
在您这样做之后，您可以安全的重构代码、实现新功能，并确保不会破坏您的旧代码。
It's usually far easier for me to write all new methods and classes than it is to break into old code and find the sections I need to change.
通常对我来说写全新的方法和类要比深入旧代码中，找出我想要修改的部分容易得多。
Since you started out valid, you can handle this incrementally, rather than dealing with both old code and your new code at the same time.
因为开始时是有效的，所以您可以逐步处理，而不是同时处理旧代码和新代码。
Reminisce about your code - There are two ways to looking at old code: "I can't believe I wrote this code" and "I can't believe I wrote this code."
回顾你的代码。在看到自己以前的代码时，通常会有两种方式：“难以至信，这代码是我写的”和“难以至信，这代码是我写的”。
There are various times when new code was introduced or old code was refactored away as indicated by sharp rises or drops in the lines of code count.
还有几次，新的代码被引入或者旧的代码被重构出去，这些可以从代码行计数的急剧升降上表现出来。
When you modify old code you have to both test your changes and then perform a set of regression tests to make sure you didn't break any of the existing code.
而当你修改旧有代码时，你不得不既要测试你更改的部分，还要进行一系列的兼容测试，以保证你没有破坏任何的旧有代码。
You cannot change the old code (otherwise it becomes a new application), so you must include forward-looking compatibility from the outset. Specifically, the code must.
因为不能修改以前的代码(否则该代码就是一个新应用程序了)，所以必须从一开始就包括向前兼容性。
Linus noted that some people were thinking that 3.0 meant it was time to start with big new features (or removal of old code), but that's not what is meant to happen.
李纳斯指出，有些人认为，3.0意味着该加入一些重大的新功能了(或移除老的代码)，但事实不是如此。
Incidentally, there's been a noticeable slowdown in compiled code on my machine very recently, even old code that previously ran quickly, hence I'm getting suspicious.
顺便说一句，出现了最近我的机器编译的代码中明显放缓，即使是旧的代码，以前跑得很快，于是我开始怀疑。
You never get it to be the same, and then you wonder whether the difference is a bug or a feature, and what did the old code do about this anyway, etc, etc, etc. Disaster.
这样绝对不会得到看上去一样的程序，你就开始想是个bug呢，还是原本特性如此呢，原来的代码到底对此事如何处理呢，等等。 绝对是灾难。
Google switched to the newer tracking code well over a year ago, and according to a Google consultant interviewed by Pingdom, the old code may be deactivated in the next few months.
Google在一年前（link）就切换到新的追踪代码（link），而根据Pindom采访的一个Google顾问估计，旧代码会在将来的几个月里无法使用。
There are several reasons that you might want to refactor code. The first is the stuff of legend: the hoary old code base for a venerable product is inherited or otherwise mysteriously appears.
您需要进行代码重构的原因可能有以下几个：传说中的第一个原因是：需要继承为某个古老产品而开发的年代久远的代码，或者突然碰到这些代码。
The community worker is patient enough to explain to the old how to use Health Code.
社区工作人员有足够的耐心向老人讲解健康码的使用方法。
For example, the faster you forget your old PIN or access code, the quicker and more accurately you will recall your new Numbers.
举例来说，越快忘记你的旧的个人识别号码或接入代码，你才能更快更准确地会记住新号码。
For example, the faster you forget your old PIN or access code, the quicker and more accurately you will recall your new Numbers.
举例来说，越快忘记你的旧的个人识别号码或接入代码，你才能更快更准确地会记住新号码。
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