问题
Originally, I've learned to specify the source code encoding in Python 2.7 this way:
# -*- coding: utf-8 -*-
Now I just noticed, that PEP263 also allows this:
# coding=utf-8
Is there any differences between these? What about editor compatiblity, cross-platform etc.?
What about Python 3? Is this comment still needed for python 3 or is any code in python 3 expected to be utf-8 by default?
回答1:
Take a look at PEP3120 which changed the default encoding of python source code to be UTF-8
For python 3.x one therefore finds in the docs:
If a comment in the first or second line of the Python script matches the regular expression coding[=:]\s*([-\w.]+), this comment is processed as an encoding declaration [...] The recommended forms of an encoding expression are:
# -*- coding: <encoding-name> -*-which is recognized also by GNU Emacs, and
# vim:fileencoding=<encoding-name>which is recognized by Bram Moolenaar’s VIM. If no encoding declaration is found, the default encoding is UTF-8
The take home message is therefore:
- python 3.x does not neccessarily need to have utf-8 specified, since it is the default
- The way the coding line is written is to some degree personal choice (only a recommendation in the docs), it only has to match the regex.
回答2:
Since Python 3 the default encoding is utf-8. You can still change the encoding using the special-formatted comment # -*- coding: <encoding name> -*-.
The docs recommend to use this coding expression as it is recognized also by GNU Emacs.
As python checks whether the first two lines are matching the regex coding[=:]\s*([-\w.]+), # coding=utf-8 works also to ensure utf-8 encoding but it is not recognized by GNU Emacs.
来源：https://stackoverflow.com/questions/52292669/python-encoding-comment-format