Python

https://docs.python.org/zh-cn/3.14
Admin
Python is a high-level, interpreted programming language known for its simplicity, readability, and...
Tokens:8,518,821
Snippets:49,274
Trust Score:10
Update:1 day ago
Show doc for...
Tokens:
Raw
### 使用补丁方法 start 和 stop 管理补丁

Source: https://docs.python.org/zh-cn/3.14/library/unittest.mock-examples.html

在 setUp 中调用 patcher.start()，在 tearDown 中调用 patcher.stop()。注意：如果 setUp 引发异常，tearDown 不会被调用，因此推荐使用 addCleanup。

```python
>>> class MyTest(unittest.TestCase):
...     def setUp(self):
...         self.patcher = patch('mymodule.foo')
...         self.mock_foo = self.patcher.start()
...
...     def test_foo(self):
...         self.assertIs(mymodule.foo, self.mock_foo)
...
...     def tearDown(self):
...         self.patcher.stop()
...
>>> MyTest('test_foo').run()
```

--------------------------------

### 在 setUp 和 tearDown 中使用 start() 和 stop() 进行多重补丁

Source: https://docs.python.org/zh-cn/3.14/library/unittest.mock.html

典型应用场景：在 TestCase 的 setUp 中启动多个补丁，在 tearDown 中停止它们。注意如果 setUp 中引发异常，tearDown 不会被调用，因此需谨慎使用。

```python
>>> class MyTest(unittest.TestCase):
...     def setUp(self):
...         self.patcher1 = patch('package.module.Class1')
...         self.patcher2 = patch('package.module.Class2')
...         self.MockClass1 = self.patcher1.start()
...         self.MockClass2 = self.patcher2.start()
...
...     def tearDown(self):
...         self.patcher1.stop()
...         self.patcher2.stop()
...
...     def test_something(self):
...         assert package.module.Class1 is self.MockClass1
...         assert package.module.Class2 is self.MockClass2
...
>>> MyTest('test_something').run()
```

--------------------------------

### setup() with dependency metadata (PEP 314)

Source: https://docs.python.org/zh-cn/3.14/whatsnew/2.5.html

Example of using the new setup() keyword parameters requires, obsoletes, and download_url to record dependency information in PKG-INFO when building a source distribution with sdist.

```python
VERSION = '1.0'
setup(name='PyPackage',
      version=VERSION,
      requires=['numarray', 'zlib (>=1.1.4)'],
      obsoletes=['OldPackage']
      download_url=('http://www.example.com/pypackage/dist/pkg-%s.tar.gz'
                    % VERSION),
     )
```

--------------------------------

### enum.Enum with start parameter

Source: https://docs.python.org/zh-cn/3.14/whatsnew/3.5.html

Shows how to use the new start parameter of enum.Enum to specify the starting value when only names are provided. The example creates an enum with values starting at 10, as shown by the output.

```python
>>> Animal = enum.Enum('Animal', 'cat dog', start=10)
>>> Animal.cat
<Animal.cat: 10>
>>> Animal.dog
<Animal.dog: 11>
```

--------------------------------

### pkgutil.get_data example

Source: https://docs.python.org/zh-cn/3.14/whatsnew/2.6.html

Shows how to use pkgutil.get_data to retrieve the contents of a resource file included with an installed package. The example prints the contents of 'exception_hierarchy.txt' from the 'test' package, displaying the exception hierarchy.

```python
>>> import pkgutil
>>> print pkgutil.get_data('test', 'exception_hierarchy.txt')
BaseException
 +-- SystemExit
 +-- KeyboardInterrupt
 +-- GeneratorExit
 +-- Exception
      +-- StopIteration
      +-- StandardError
 ...
```

--------------------------------

### math.prod() example

Source: https://docs.python.org/zh-cn/3.14/whatsnew/3.8.html

Shows how to use math.prod() to multiply an iterable of numbers, with an optional start value (default 1). The example multiplies likelihoods with a prior of 0.8, resulting in 0.126.

```python
>>> prior = 0.8
>>> likelihoods = [0.625, 0.84, 0.30]
>>> math.prod(likelihoods, start=prior)
0.126
```

--------------------------------

### gzip.compress and gzip.decompress example

Source: https://docs.python.org/zh-cn/3.14/whatsnew/3.2.html

Shows how to compress and decompress bytes in memory using gzip.compress() and gzip.decompress(). Text must be encoded to bytes before compression and decoded after decompression. The example demonstrates the round-trip and shows the length reduction.

```python
>>> import gzip
>>> s = 'Three shall be the number thou shalt count, '
>>> s += 'and the number of the counting shall be three'
>>> b = s.encode()                        # convert to utf-8
>>> len(b)
89
>>> c = gzip.compress(b)
>>> len(c)
77
>>> gzip.decompress(c).decode()[:42]      # decompress and convert to text
'Three shall be the number thou shalt count'
```

--------------------------------

### Run sysconfig from the command line to display platform paths and variables

Source: https://docs.python.org/zh-cn/3.14/whatsnew/3.2.html

Invoke the sysconfig module with python -m sysconfig to print the current platform, Python version, installation scheme, paths, and configuration variables. The output shown is from a Windows installation (scheme 'nt') and includes paths like 'data' and 'include' as well as variables such as BINDIR and EXE.

```text
C:\Python32>python -m sysconfig
Platform: "win32"
Python version: "3.2"
Current installation scheme: "nt"

Paths:
        data = "C:\Python32"
        include = "C:\Python32\Include"
        platinclude = "C:\Python32\Include"
        platlib = "C:\Python32\Lib\site-packages"
        platstdlib = "C:\Python32\Lib"
        purelib = "C:\Python32\Lib\site-packages"
        scripts = "C:\Python32\Scripts"
        stdlib = "C:\Python32\Lib"

Variables:
        BINDIR = "C:\Python32"
        BINLIBDEST = "C:\Python32\Lib"
        EXE = ".exe"
        INCLUDEPY = "C:\Python32\Include"
        LIBDEST = "C:\Python32\Lib"
        SO = ".pyd"
        VERSION = "32"
        abiflags = ""
        base = "C:\Python32"
        exec_prefix = "C:\Python32"
        platbase = "C:\Python32"
        prefix = "C:\Python32"
        projectbase = "C:\Python32"
        py_version = "3.2"
        py_version_nodot = "32"
        py_version_short = "3.2"
        srcdir = "C:\Python32"
        userbase = "C:\Documents and Settings\Raymond\Application Data\Python"
```

--------------------------------

### logging.basicConfig style parameter examples

Source: https://docs.python.org/zh-cn/3.14/whatsnew/3.2.html

Shows three equivalent ways to configure logging.basicConfig with different style values: '%', '{', and '$'. The default is '%' for traditional %-formatting, '{' uses str.format(), and '$' uses string.Template. These examples are from the Python 3.2 What's New documentation.

```python
>>> from logging import basicConfig
>>> basicConfig(style='%', format="%(name)s -> %(levelname)s: %(message)s")
>>> basicConfig(style='{', format="{name} -> {levelname} {message}")
>>> basicConfig(style='$', format="$name -> $levelname: $message")
```

--------------------------------

### pathlib.Path.samefile example

Source: https://docs.python.org/zh-cn/3.14/whatsnew/3.5.html

Demonstrates using Path.samefile() to check if two paths (Path objects or strings) refer to the same file. The example shows that '/etc/hosts' and '/etc/../etc/hosts' are the same file.

```python
>>> import pathlib
>>> p1 = pathlib.Path('/etc/hosts')
>>> p2 = pathlib.Path('/etc/../etc/hosts')
>>> p1.samefile(p2)
True
```

--------------------------------

### statistics.NormalDist example: temperature data analysis

Source: https://docs.python.org/zh-cn/3.14/whatsnew/3.8.html

Demonstrates creating a NormalDist from sample data, computing mean and standard deviation, calculating CDF and PDF, adding distributions, scaling, and generating random samples. The example uses temperature data and shows the output of each operation.

```python
>>> temperature_feb = NormalDist.from_samples([4, 12, -3, 2, 7, 14])
>>> temperature_feb.mean
6.0
>>> temperature_feb.stdev
6.356099432828281

>>> temperature_feb.cdf(3)            # 在 3 度以下的几率
0.3184678262814532
>>> # 为 7 度与为 10 度的相对几率
>>> temperature_feb.pdf(7) / temperature_feb.pdf(10)
1.2039930378537762

>>> el_niño = NormalDist(4, 2.5)
>>> temperature_feb += el_niño        # 加入一个气候效应
>>> temperature_feb
NormalDist(mu=10.0, sigma=6.830080526611674)

>>> temperature_feb * (9/5) + 32      # 转换为华氏度
NormalDist(mu=50.0, sigma=12.294144947901014)
>>> temperature_feb.samples(3)        # 生成随机样本
[7.672102882379219, 12.000027119750287, 4.647488369766392]
```

--------------------------------

### math.isqrt() example

Source: https://docs.python.org/zh-cn/3.14/whatsnew/3.8.html

Shows the new isqrt() function for exact integer square roots. It is faster than floor(sqrt(n)) but slower than math.sqrt(). The example demonstrates that isqrt(s-1) returns the correct value while floor(sqrt(s-1)) is incorrect.

```python
>>> r = 650320427
>>> s = r ** 2
>>> isqrt(s - 1)         # 正确
650320426
>>> floor(sqrt(s - 1))   # 不正确
650320427
```

--------------------------------

### itertools.product example

Source: https://docs.python.org/zh-cn/3.14/whatsnew/2.6.html

Shows the Cartesian product of two lists using itertools.product.

```python
>>> list(itertools.product([1,2,3], [4,5,6]))
[(1, 4), (1, 5), (1, 6),
 (2, 4), (2, 5), (2, 6),
 (3, 4), (3, 5), (3, 6)]
```

--------------------------------

### Get angle towards a point with turtle.towards()

Source: https://docs.python.org/zh-cn/3.14/library/turtle.html

Returns the angle from the turtle's position to a given point, measured from the turtle's start orientation. The example moves the turtle to (10,10) and then gets the angle towards (0,0).

```python
>>> turtle.goto(10, 10)
>>> turtle.towards(0,0)
225.0
```

--------------------------------

### setup.py 脚本（C 扩展）

Source: https://docs.python.org/zh-cn/3.14/whatsnew/2.0.html

当软件包含 C 扩展时，使用此 setup.py 脚本。它使用 Extension 类定义扩展模块，并指定宏、包含目录和源文件。

```python
from distutils.core import setup, Extension

expat_extension = Extension('xml.parsers.pyexpat',
     define_macros = [('XML_NS', None)],
     include_dirs = [ 'extensions/expat/xmltok',
                      'extensions/expat/xmlparse' ],
     sources = [ 'extensions/pyexpat.c',
                 'extensions/expat/xmltok/xmltok.c',
                 'extensions/expat/xmltok/xmlrole.c', ]
       )
setup (name = "PyXML", version = "0.5.4",
       ext_modules =[ expat_extension ] )

```

--------------------------------

### Get distribution version with importlib.metadata.version()

Source: https://docs.python.org/zh-cn/3.14/library/importlib.metadata.html

Returns the installed version of a distribution as a string. Raises PackageNotFoundError if the distribution is not installed.

```python
>>> version('wheel')
'0.32.3'
```

--------------------------------

### setup.py 脚本（包含多个包）

Source: https://docs.python.org/zh-cn/3.14/whatsnew/2.0.html

当软件由多个包组成时，使用此 setup.py 脚本。它使用 packages 参数列出所有包。

```python
from distutils.core import setup
setup (name = "foo", version = "1.0",
       packages = ["package", "package.subpackage"])

```

--------------------------------

### 最小化 setup.py 脚本（纯 Python 模块）

Source: https://docs.python.org/zh-cn/3.14/whatsnew/2.0.html

当软件仅包含 .py 文件时，使用此最小化 setup.py 脚本。它使用 distutils.core.setup 并指定 py_modules 参数。

```python
from distutils.core import setup
setup (name = "foo", version = "1.0",
       py_modules = ["module1", "module2"])

```

--------------------------------

### Get bounds of compression_level

Source: https://docs.python.org/zh-cn/3.14/library/compression.zstd.html

Example showing how to get the lower and upper bounds of the compression_level parameter using the bounds() method.

```python
lower, upper = CompressionParameter.compression_level.bounds()
```

--------------------------------

### 在 Setup 文件中添加额外链接库

Source: https://docs.python.org/zh-cn/3.14/extending/extending.html

如果模块需要额外的链接库，可在配置文件中列出，例如 -lX11。

```makefile
spam spammodule.o -lX11
```

--------------------------------

### 更新 setup.py 以包含 custom2 模块

Source: https://docs.python.org/zh-cn/3.14/extending/newtypes_tutorial.html

更新 setup.py 以构建 custom 和 custom2 两个扩展模块。

```python
from setuptools import Extension, setup
setup(ext_modules=[
    Extension("custom", ["custom.c"]),
    Extension("custom2", ["custom2.c"]),
])
```

--------------------------------

### Start a BaseManager server with serve_forever()

Source: https://docs.python.org/zh-cn/3.14/library/multiprocessing.html

Creates a BaseManager with address and authkey, gets the server, and runs serve_forever() to start serving. The server has an additional 'address' attribute.

```python
>>> from multiprocessing.managers import BaseManager
>>> manager = BaseManager(address=('', 50000), authkey=b'abc')
>>> server = manager.get_server()
>>> server.serve_forever()
```

--------------------------------

### GET request with http.client

Source: https://docs.python.org/zh-cn/3.14/library/http.client.html

Shows a complete GET request session: connect to www.python.org, send a GET request, read the response, and demonstrate chunked reading. Also includes an invalid request example that returns a 404 status.

```python
>>> import http.client
>>> conn = http.client.HTTPSConnection("www.python.org")
>>> conn.request("GET", "/")
>>> r1 = conn.getresponse()
>>> print(r1.status, r1.reason)
200 OK
>>> data1 = r1.read()  # 这将返回全部内容。
>>> # 下面的例子演示了分块读取数据。
>>> conn.request("GET", "/")
>>> r1 = conn.getresponse()
>>> while chunk := r1.read(200):
...     print(repr(chunk))
b'<!doctype html>\n<!--[if"...
...
>>> # 无效请求的例子
>>> conn = http.client.HTTPSConnection("docs.python.org")
>>> conn.request("GET", "/parrot.spam")
>>> r2 = conn.getresponse()
>>> print(r2.status, r2.reason)
404 Not Found
>>> data2 = r2.read()
>>> conn.close()
```

--------------------------------

### 通过 setup 参数访问用户定义函数

Source: https://docs.python.org/zh-cn/3.14/library/timeit.html

在 setup 参数中使用 import 语句导入用户定义的函数，以便 timeit 模块可以访问它。

```python
def test():
    """愚笨的测试函数"""
    L = [i for i in range(100)]

if __name__ == '__main__':
    import timeit
    print(timeit.timeit("test()", setup="from __main__ import test"))
```

--------------------------------

### 命令行计时：使用 setup 语句

Source: https://docs.python.org/zh-cn/3.14/library/timeit.html

通过命令行使用 -s 选项提供 setup 语句，测量字符成员测试和 find 方法的性能。输出显示循环次数、重复次数和最佳平均耗时。

```bash
$ python -m timeit -s "text = 'sample string'; char = 'g'" "char in text"
5000000 loops, best of 5: 0.0877 usec per loop
$ python -m timeit -s "text = 'sample string'; char = 'g'" "text.find(char)"
1000000 loops, best of 5: 0.342 usec per loop
```

--------------------------------

### multiprocessing.get_start_method()

Source: https://docs.python.org/zh-cn/3.14/genindex-all.html

Function to get the current start method for multiprocessing. Part of the multiprocessing module.

```APIDOC
## multiprocessing.get_start_method()

### Description
Returns the current start method used for starting child processes. This function is part of the multiprocessing module.

### Method
- (Python function)

### Module
multiprocessing

### Signature
`get_start_method(allow_none=False)`

### Parameters
- **allow_none** (bool) - Optional - If True, returns None if no start method has been set. Default is False.

### Returns
- **method** (str) - The name of the start method (e.g., 'fork', 'spawn', 'forkserver').

### Reference
[Python documentation](https://docs.python.org/zh-cn/3.14/library/multiprocessing.html#multiprocessing.get_start_method)
```

--------------------------------

### 使用 setUp 方法共享前置操作

Source: https://docs.python.org/zh-cn/3.14/library/unittest.html

将多个测试的公共初始化代码放入 setUp 方法，测试框架会在每个测试前自动调用。示例包含两个测试方法，分别验证默认尺寸和调整尺寸后的结果。

```python
import unittest

class WidgetTestCase(unittest.TestCase):
    def setUp(self):
        self.widget = Widget('The widget')

    def test_default_widget_size(self):
        self.assertEqual(self.widget.size(), (50,50),
                         'incorrect default size')

    def test_widget_resize(self):
        self.widget.resize(100,150)
        self.assertEqual(self.widget.size(), (100,150),
                         'wrong size after resize')
```

--------------------------------

### Get current heading with turtle.heading()

Source: https://docs.python.org/zh-cn/3.14/library/turtle.html

Returns the turtle's current heading, which depends on the turtle mode. The example homes the turtle, turns left 67 degrees, and gets the heading.

```python
>>> turtle.home()
>>> turtle.left(67)
>>> turtle.heading()
67.0
```

--------------------------------

### os.startfile(path[, operation][, arguments][, cwd][, show_cmd])

Source: https://docs.python.org/zh-cn/3.14/library/os.html

使用关联的应用程序打开文件。当未指定 operation 时，类似于在 Windows 资源管理器中双击文件。可指定操作动词如 'open'、'print'、'edit' 等。

```APIDOC
## os.startfile(path[, operation][, arguments][, cwd][, show_cmd])

### Description
使用已关联的应用程序打开文件。当未指定 operation 时，类似于在 Windows 资源管理器中双击文件，或使用 start 命令。可指定其他操作动词，如 'open'、'print'、'edit'（用于文件）以及 'explore'、'find'（用于目录）。

### Method
Function call

### Endpoint
os.startfile(path[, operation][, arguments][, cwd][, show_cmd])

### Parameters
#### Path Parameters
- **path** (str or path-like) - Required - 要打开的文件或目录的路径。可以是相对路径或绝对路径。

#### Optional Parameters
- **operation** (str) - Optional - 要对文件执行的操作动词，如 'open'、'print'、'edit' 等。
- **arguments** (str) - Optional - 启动应用程序时传入的参数字符串。
- **cwd** (str or path-like) - Optional - 工作目录，应为绝对路径。相对路径将基于此参数解析。
- **show_cmd** (int) - Optional - 覆盖默认窗口样式的整数，值应为 Win32 ShellExecute() 函数支持的整数。

### Request Example
```python
import os
os.startfile('document.txt')
os.startfile('document.txt', 'print')
```

### Response
#### Success Response
无返回值。函数在关联应用程序启动后立即返回。

### Notes
- 仅适用于 Windows。
- 如果 Win32 ShellExecute() 函数无法解析，将引发 NotImplementedError。
- 引发审计事件 os.startfile 和 os.startfile/2。

```
Tokens:
Raw