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Merge pull request #21033 from wxy/20191230-Namespaces-are-the-shamash-candle-of-the-Zen-of-Python
TSL&PRF:sources/tech/20191230 Namespaces are the shamash candle of the Zen of Python.md
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[#]: collector: (lujun9972)
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[#]: translator: (wxy)
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[#]: subject: (Namespaces are the shamash candle of the Zen of Python)
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[#]: via: (https://opensource.com/article/19/12/zen-python-namespaces)
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[#]: author: (Moshe Zadka https://opensource.com/users/moshez)
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Namespaces are the shamash candle of the Zen of Python
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======
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This is part of a special series about the Zen of Python focusing on one bonus principle: namespaces.
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![Person programming on a laptop on a building][1]
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Hanukkah famously has eight nights of celebration. The Hanukkah menorah, however, has nine candles: eight regular candles and a ninth that is always offset. It is called the **shamash** or **shamos**, which loosely translates to meaning "servant" or "janitor."
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The shamos is the candle that lights all the others: it is the only candle whose fire can be used, not just watched. As we wrap up our series on the Zen of Python, I see how namespaces provide a similar service.
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### Namespaces in Python
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Python uses namespaces for everything. Though simple, they are sparse data structures—which is often the best way to achieve a goal.
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> A _namespace_ is a mapping from names to objects.
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>
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> — [Python.org][2]
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Modules are namespaces. This means that correctly predicting module semantics often just requires familiarity with how Python namespaces work. Classes are namespaces. Objects are namespaces. Functions have access to their local namespace, their parent namespace, and the global namespace.
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The simple model, where the **.** operator accesses an object, which in turn will usually, but not always, do some sort of dictionary lookup, makes Python hard to optimize, but easy to explain.
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Indeed, some third-party modules take this guideline and run with it. For example, the** [variants][3]** package turns functions into namespaces of "related functionality." It is a good example of how the [Zen of Python][4] can inspire new abstractions.
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### In conclusion
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Thank you for joining me on this Hanukkah-inspired exploration of [my favorite language][5]. Go forth and meditate on the Zen until you reach enlightenment.
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--------------------------------------------------------------------------------
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via: https://opensource.com/article/19/12/zen-python-namespaces
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作者：[Moshe Zadka][a]
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选题：[lujun9972][b]
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译者：[译者ID](https://github.com/译者ID)
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校对：[校对者ID](https://github.com/校对者ID)
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本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
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[a]: https://opensource.com/users/moshez
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[b]: https://github.com/lujun9972
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[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/computer_code_programming_laptop.jpg?itok=ormv35tV (Person programming on a laptop on a building)
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[2]: https://docs.python.org/3/tutorial/classes.html
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[3]: https://pypi.org/project/variants/
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[4]: https://www.python.org/dev/peps/pep-0020/
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[5]: https://opensource.com/article/19/10/why-love-python
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[#]: collector: (lujun9972)
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[#]: translator: (wxy)
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[#]: reviewer: (wxy)
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[#]: publisher: ( )
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[#]: url: ( )
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[#]: subject: (Namespaces are the shamash candle of the Zen of Python)
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[#]: via: (https://opensource.com/article/19/12/zen-python-namespaces)
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[#]: author: (Moshe Zadka https://opensource.com/users/moshez)
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命名空间是 Python 之禅的精髓
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======
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> 这是 Python 之禅特别系列的一部分，重点是一个额外的原则：命名空间。
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![在建筑物上的笔记本电脑上编程的人][1]
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著名的<ruby>光明节<rt>Hanukkah</rt></ruby>有八个晚上的庆祝活动。然而，光明节的灯台有九根蜡烛：八根普通蜡烛和总是偏移的第九根蜡烛。它被称为 “shamash” 或 “shamos”，大致可以翻译为“仆人”或“看门人”的意思。
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shamos 是点燃所有其它蜡烛的蜡烛：它是唯一一支可以用火的蜡烛，而不仅仅是观看。当我们结束关于 Python 之禅系列时，我看到命名空间提供了类似的作用。
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### Python 中的命名空间
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Python 使用命名空间来处理一切。虽然简单，但它们是稀疏的数据结构 —— 这通常是实现目标的最佳方式。
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> *命名空间* 是一个从名字到对象的映射。
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>
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> —— [Python.org][2]
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模块是命名空间。这意味着正确地预测模块语义通常只需要熟悉 Python 命名空间的工作方式。类是命名空间，对象是命名空间。函数可以访问它们的本地命名空间、父命名空间和全局命名空间。
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这个简单的模型，即用 `.` 操作符访问一个对象，而这个对象又通常（但并不总是）会进行某种字典查找，这使得 Python 很难优化，但很容易解释。
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事实上，一些第三方模块也采取了这个准则，并以此来运行。例如，[variants][3] 包把函数变成了“相关功能”的命名空间。这是一个很好的例子，说明 [Python 之禅][4] 是如何激发新的抽象的。
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### 结语
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感谢你和我一起参加这次以光明节为灵感的 [我最喜欢的语言][5] 的探索。
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静心参禅，直至悟道。
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--------------------------------------------------------------------------------
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via: https://opensource.com/article/19/12/zen-python-namespaces
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作者：[Moshe Zadka][a]
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选题：[lujun9972][b]
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译者：[wxy](https://github.com/wxy)
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校对：[wxy](https://github.com/wxy)
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本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
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[a]: https://opensource.com/users/moshez
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[b]: https://github.com/lujun9972
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[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/computer_code_programming_laptop.jpg?itok=ormv35tV (Person programming on a laptop on a building)
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[2]: https://docs.python.org/3/tutorial/classes.html
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[3]: https://pypi.org/project/variants/
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[4]: https://www.python.org/dev/peps/pep-0020/
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[5]: https://opensource.com/article/19/10/why-love-python
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