>>> from env_helper import info; info()
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运行环境：
Linux发行版本: Debian GNU/Linux 12 (bookworm)
操作系统内核: Linux-6.1.0-18-amd64-x86_64-with-glibc2.36
Python版本: 3.11.2
1.2. Follow the PEP 8 Style Guide¶
Python Enhancement Proposal #8, otherwise known as PEP 8, is the style guide for how to format Python code. You are welcome to write Python code any way you want, as long as it has valid syntax. However, using a consistent style makes your code more approachable and easier to read. Sharing a common style with other Python programmers in the larger community facilitates collaboration on projects. But even if you are the only one who will ever read your code, following the style guide will make it easier for you to change things later, and can help you avoid many common errors.
PEP 8 provides a wealth of details about how to write clear Python code. It continues to be updated as the Python language evolves. It’s worth reading the whole guide online (https://www.python.org/dev/peps/pep-0008/). Here are a few rules you should be sure to follow.
1.2.1. Whitespace¶
In Python, whitespace is syntactically significant. Python programmers are especially sensitive to the effects of whitespace on code clarity. Follow these guidelines related to whitespace:
Use spaces instead of tabs for indentation.
Use four spaces for each level of syntactically significant indenting.
Lines should be 79 characters in length or less.
Continuations of long expressions onto additional lines should be indented by four extra spaces from their normal indentation level.
In a file, functions and classes should be separated by two blank lines.
In a class, methods should be separated by one blank line.
In a dictionary, put no whitespace between each key and colon, and put a single space before the corresponding value if it fits on the same line.
Put one—and only one—space before and after the = operator in a variable assignment.
For type annotations, ensure that there is no separation between the variable name and the colon, and use a space before the type information.
1.2.2. Naming¶
PEP 8 suggests unique styles of naming for different parts in the language. These conventions make it easy to distinguish which type corresponds to each name when reading code. Follow these guidelines related to naming:
Functions, variables, and attributes should be in lowercase_underscore format.
Protected instance attributes should be in _leading_underscore format.
Private instance attributes should be in __double_leading_underscore format.
Classes (including exceptions) should be in CapitalizedWord format.
Module-level constants should be in ALL_CAPS format.
Instance methods in classes should use self, which refers to the object, as the name of the first parameter.
Class methods should use cls, which refers to the class, as the name of the first parameter.
1.2.3. Expressions and Statements¶
The Zen of Python states: “There should be one—and preferably only one—obvious way to do it.” PEP 8 attempts to codify this style in its guidance for expressions and statements:
Use inline negation (if a is not b) instead of negation of positive expressions (if not a is b).
Don’t check for empty containers or sequences (like [] or ’’) by comparing the length to zero (if len(somelist) == 0). Use if not somelist and assume that empty values will implicitly evaluate to False.
The same thing goes for non-empty containers or sequences (like [1] or ‘hi’). The statement if somelist is implicitly True for non-empty values.
Avoid single-line if statements, for and while loops, and except compound statements. Spread these over multiple lines for clarity.
If you can’t fit an expression on one line, surround it with parentheses and add line breaks and indentation to make it easier to read.
Prefer surrounding multiline expressions with parentheses over using the line continuation character.
1.2.4. Imports¶
PEP 8 suggests some guidelines for how to import modules and use them in your code:
Always put import statements (including from x import y) at the top of a file.
Always use absolute names for modules when importing them, not names relative to the current module’s own path. For example, to import the foo module from within the bar package, you should use from bar import foo, not just import foo.
If you must do relative imports, use the explicit syntax from . import foo.
Imports should be in sections in the following order: standard library modules, third-party modules, your own modules. Each subsection should have imports in alphabetical order.
Note
The Pylint tool (https://www.pylint.org) is a popular static analyzer for Python source code. Pylint provides automated enforcement of the PEP 8 style guide and detects many other types of common errors in Python programs. Many IDEs and editors also include linting tools or support similar plug-ins.
1.2.5. Things to Remember¶
Always follow the Python Enhancement Proposal #8 (PEP 8) style guide when writing Python code.
Sharing a common style with the larger Python community facilitates collaboration with others.
Using a consistent style makes it easier to modify your own code later.