mirror of
https://github.com/LCTT/TranslateProject.git
synced 2024-12-26 21:30:55 +08:00
translated
This commit is contained in:
geekpi
parent
c8861e0ce5
commit
c327fbde15
@ -1,107 +0,0 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (geekpi)
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Say goodbye to boilerplate in Python with attrs)
|
||||
[#]: via: (https://opensource.com/article/19/5/python-attrs)
|
||||
[#]: author: (Moshe Zadka https://opensource.com/users/moshez/users/moshez)
|
||||
|
||||
Say goodbye to boilerplate in Python with attrs
|
||||
======
|
||||
Learn more about solving common Python problems in our series covering
|
||||
seven PyPI libraries.
|
||||
![Programming at a browser, orange hands][1]
|
||||
|
||||
Python is one of the most [popular programming languages][2] in use today—and for good reasons: it's open source, it has a wide range of uses (such as web programming, business applications, games, scientific programming, and much more), and it has a vibrant and dedicated community supporting it. This community is the reason we have such a large, diverse range of software packages available in the [Python Package Index][3] (PyPI) to extend and improve Python and solve the inevitable glitches that crop up.
|
||||
|
||||
In this series, we'll look at seven PyPI libraries that can help you solve common Python problems. Today, we'll examine [**attrs**][4], a Python package that helps you write concise, correct code quickly.
|
||||
|
||||
### attrs
|
||||
|
||||
If you have been using Python for any length of time, you are probably used to writing code like:
|
||||
|
||||
|
||||
```
|
||||
class Book(object):
|
||||
|
||||
def __init__(self, isbn, name, author):
|
||||
self.isbn = isbn
|
||||
self.name = name
|
||||
self.author = author
|
||||
```
|
||||
|
||||
Then you write a **__repr__** function; otherwise, it would be hard to log instances of **Book** :
|
||||
|
||||
|
||||
```
|
||||
def __repr__(self):
|
||||
return f"Book({self.isbn}, {self.name}, {self.author})"
|
||||
```
|
||||
|
||||
Next, you write a nice docstring documenting the expected types. But you notice you forgot to add the **edition** and **published_year** attributes, so you have to modify them in five places.
|
||||
|
||||
What if you didn't have to?
|
||||
|
||||
|
||||
```
|
||||
@attr.s(auto_attribs=True)
|
||||
class Book(object):
|
||||
isbn: str
|
||||
name: str
|
||||
author: str
|
||||
published_year: int
|
||||
edition: int
|
||||
```
|
||||
|
||||
Annotating the attributes with types using the new type annotation syntax, **attrs** detects the annotations and creates a class.
|
||||
|
||||
ISBNs have a specific format. What if we want to enforce that format?
|
||||
|
||||
|
||||
```
|
||||
@attr.s(auto_attribs=True)
|
||||
class Book(object):
|
||||
isbn: str = attr.ib()
|
||||
@isbn.validator
|
||||
def pattern_match(self, attribute, value):
|
||||
m = re.match(r"^(\d{3}-)\d{1,3}-\d{2,3}-\d{1,7}-\d$", value)
|
||||
if not m:
|
||||
raise ValueError("incorrect format for isbn", value)
|
||||
name: str
|
||||
author: str
|
||||
published_year: int
|
||||
edition: int
|
||||
```
|
||||
|
||||
The **attrs** library also has great support for [immutability-style programming][5]. Changing the first line to **@attr.s(auto_attribs=True, frozen=True)** means that **Book** is now immutable: trying to modify an attribute will raise an exception. Instead, we can get a _new_ instance with modification using **attr.evolve(old_book, published_year=old_book.published_year+1)** , for example, if we need to push publication forward by a year.
|
||||
|
||||
In the next article in this series, we'll look at **singledispatch** , a library that allows you to add methods to Python libraries retroactively.
|
||||
|
||||
#### Review the previous articles in this series
|
||||
|
||||
* [Cython][6]
|
||||
* [Black][7]
|
||||
|
||||
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/19/5/python-attrs
|
||||
|
||||
作者：[Moshe Zadka ][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/moshez/users/moshez
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/programming_code_keyboard_orange_hands.png?itok=G6tJ_64Y (Programming at a browser, orange hands)
|
||||
[2]: https://opensource.com/article/18/5/numbers-python-community-trends
|
||||
[3]: https://pypi.org/
|
||||
[4]: https://pypi.org/project/attrs/
|
||||
[5]: https://opensource.com/article/18/10/functional-programming-python-immutable-data-structures
|
||||
[6]: https://opensource.com/article/19/4/7-python-problems-solved-cython
|
||||
[7]: https://opensource.com/article/19/4/python-problems-solved-black
|
||||
@ -0,0 +1,106 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (geekpi)
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Say goodbye to boilerplate in Python with attrs)
|
||||
[#]: via: (https://opensource.com/article/19/5/python-attrs)
|
||||
[#]: author: (Moshe Zadka https://opensource.com/users/moshez/users/moshez)
|
||||
|
||||
使用 attrs 来告别 Python 中的样板
|
||||
======
|
||||
在我们覆盖 7 个 PyPI 库的系列文章中了解更多解决 Python 问题的信息。
|
||||
![Programming at a browser, orange hands][1]
|
||||
|
||||
Python是当今使用最多[流行的编程语言] [2]之一 - 并且有充分的理由：它是开源的，它具有广泛的用途（例如Web编程，业务应用程序，游戏，科学编程等等）更多），它有一个充满活力和专注的社区支持它。这个社区是我们在[Python Package Index] [3]（PyPI）中提供如此庞大，多样化的软件包的原因，以扩展和改进Python并解决不可避免的问题。
|
||||
|
||||
在本系列中，我们将介绍七个可以帮助你解决常见 Python 问题的 PyPI 库。今天，我们将研究 [**attrs**][4]，这是一个帮助你快速编写简洁，正确的代码的 Python 包。
|
||||
|
||||
### attrs
|
||||
|
||||
如果你已经写过一段时间的 Python，那么你可能习惯这样写代码：
|
||||
|
||||
|
||||
```
|
||||
class Book(object):
|
||||
|
||||
def __init__(self, isbn, name, author):
|
||||
self.isbn = isbn
|
||||
self.name = name
|
||||
self.author = author
|
||||
```
|
||||
|
||||
接着写一个 **__repr__** 函数。否则，很难记录 **Book** 的实例：
|
||||
|
||||
|
||||
```
|
||||
def __repr__(self):
|
||||
return f"Book({self.isbn}, {self.name}, {self.author})"
|
||||
```
|
||||
|
||||
接下来你会写一个好看的 docstring 来记录期望的类型。但是你注意到你忘了添加 **edition** 和 **published_year** 属性，所以你必须在五个地方修改它们。
|
||||
|
||||
如果你不必这么做如何？
|
||||
|
||||
|
||||
```
|
||||
@attr.s(auto_attribs=True)
|
||||
class Book(object):
|
||||
isbn: str
|
||||
name: str
|
||||
author: str
|
||||
published_year: int
|
||||
edition: int
|
||||
```
|
||||
|
||||
使用新的类型注释语法注释类型属性，**attrs** 会检测注释并创建一个类。
|
||||
|
||||
ISBN 有特定格式。如果我们想强行使用该格式怎么办？
|
||||
|
||||
|
||||
```
|
||||
@attr.s(auto_attribs=True)
|
||||
class Book(object):
|
||||
isbn: str = attr.ib()
|
||||
@isbn.validator
|
||||
def pattern_match(self, attribute, value):
|
||||
m = re.match(r"^(\d{3}-)\d{1,3}-\d{2,3}-\d{1,7}-\d$", value)
|
||||
if not m:
|
||||
raise ValueError("incorrect format for isbn", value)
|
||||
name: str
|
||||
author: str
|
||||
published_year: int
|
||||
edition: int
|
||||
```
|
||||
|
||||
**attrs** 库也对[不可变风格编程][5]支持良好。将第一行改成 **@attr.s(auto_attribs=True, frozen=True)** 意味着 **Book** 现在是不可变的：尝试修改一个属性将会引发一个异常。相反，比如，如果希望将发布日期向后一年，我们可以修改成 **attr.evolve(old_book, published_year=old_book.published_year+1)** 来得到一个_新的_实例。
|
||||
|
||||
本系列的下一篇文章我们将来看下 **singledispatch**，一个能让你向 Python 库添加方法的库。
|
||||
|
||||
#### 查看本系列先前的文章
|
||||
|
||||
* [Cython][6]
|
||||
* [Black][7]
|
||||
|
||||
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/19/5/python-attrs
|
||||
|
||||
作者：[Moshe Zadka ][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[geekpi](https://github.com/geekpi)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/moshez/users/moshez
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/programming_code_keyboard_orange_hands.png?itok=G6tJ_64Y (Programming at a browser, orange hands)
|
||||
[2]: https://opensource.com/article/18/5/numbers-python-community-trends
|
||||
[3]: https://pypi.org/
|
||||
[4]: https://pypi.org/project/attrs/
|
||||
[5]: https://opensource.com/article/18/10/functional-programming-python-immutable-data-structures
|
||||
[6]: https://opensource.com/article/19/4/7-python-problems-solved-cython
|
||||
[7]: https://opensource.com/article/19/4/python-problems-solved-black
|
||||
Loading…
Reference in New Issue
Block a user