Should I start a py file with coding information? [duplicate]

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Can you tell me how I should formalize my .py file.

.py

From some sources I've found that all files should start with:

# coding : utf-8
# PEP-8


Some people on GitHub do this:

# -*- coding: utf-8 -*-


However, Google for example doesn't use either of these and start files with license information:

# Copyright (C) 2018 Google Inc.
# Licensed under http://www.apache.org/licenses/LICENSE-2.0 <see LICENSE file>


What is the best and accepted way?

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# PEP-8

pep8

pep8

pycodestyle

1 Answer
1

It depends.

Python 2 used ASCII as default encoding for source files.

Python 3's default is UTF-8.

So, if you intend to only support Python 3+ then you don't have to declare the utf-8 encoding as it is already the default.

If you intend to support Python 2 as well and you have non-ASCII string literals then you should declare an encoding.

If your text editor also needs a coding declaration (e.g., if your Unix locale is set to, say, Latin-1, but your code is UTF-8), Python's lenient syntax allows a single declaration to be used for both—e.g., # -*- coding: utf-8 -*- is recognized by both emacs and Python.

# -*- coding: utf-8 -*-

Some official information:

Python 3's docs about unicode support: https://docs.python.org/3/howto/unicode.html#python-s-unicode-support

PEP 263 that introduced the encoding declaration syntax: https://www.python.org/dev/peps/pep-0263/

PEP 3210 about changing the default encoding from ASCII to UTF-8 starting from Python 3.0: https://www.python.org/dev/peps/pep-3120/