Manual:Coding conventions/Python/ja

このページでは、MediaWiki プロジェクトまたはサポート プロジェクトの一部である Python プロジェクト群のコーディング規約について説明します.

前文
まず、コード標準は単なるガイドラインであり、正当な理由がある場合は違反する可能性があることを忘れないでください.


 * 厳格な遵守のために、厳格な遵守よりも読みやすさと自明性を目指してください.
 * コードは、書かれるよりもはるかに頻繁に読まれます.
 * 既存のコードと一貫性を保ちつつ、最善の判断を下してください. 既存のコードを修正するのがそれほど難しくない場合は、ja:WP:BOLD.

この文書で網羅されていないものについては、一般的な方法について Python Enhancement Proposal 0008 を参照してください. 以下の節は、ほとんどの場合、PEP8 の最も一般的に参照される部分の要約です.

Python のバージョン
The minimum supported version is 2.7, but in special cases it is ok to support older versions.

If you have not already, you should change to Python 3 for local development.

空白類
Lines should be indented with 4 spaces.

Lines at the end of files should end with a newline, just like every other line in the file.

Try to keep lines under 80 characters long, but aim for readability and obviousness over strict adherence for the sake of strict adherence. Shorter lines are just a general side effect of good idiomatic python - short but properly scoped descriptive names, avoiding staircase code, etc. When splitting up lines, pick the most obviously unambiguous method possible for the situation.

Module structure
The standard way to distribute python modules is to create a  file and leverage a library called "distribute". There are modules that will generate the structure of a base project for you, a deprecated one is  which is no longer maintained. A replacement is pythong.

In general module structure should look like this: newproject ├── bin ├── distribute_setup.py ├── docs ├── newproject │    └── __init__.py ├── setup.py └── tests ├── __init__.py      └── newproject_tests.py

Imports
Within a file it's generally a good idea to organize your imports in some fashion. Typically alphabetical order is favored, but this can become unwieldy when importing a large number of libraries. To help avoid this, it's good to separate out imports in this fashion, with each block separated from the others by an empty line:


 * Standard library imports
 * Third party imports
 * Your library imports

Here are some patterns to avoid:

Imports expanded example
Here is a more detailed abstracted version (the comments are just for explanation purposes):

Docstrings and function annotation
Generally all but the simplest functions should have docstrings. These are standardized in PEP 257

This makes it possible to automatically generate docs, as well as use Python's built-in  function.

In Python 3.3 and above PEP 3107 specifies syntax for function annotations.

Function annotations do not have a completely set use case, but a common emerging case is for improved help docs and for type annotation.

Naming conflicts
Conflicting with builtins is a somewhat common problem. There are some builtin names (like  and  ) that you may want to use in your code. The PEP8 way to deal with these conflicts is by appending an underscore to the name, such as  or   (although if you're naming a variable   that may be a code smell).

If you find yourself in conflict with the name of some part of another module,  is your friend.