Correct way to define Python source code encoding

Question

PEP 263 defines how to declare Python source code encoding.

Normally, the first 2 lines of a Python file should start with:

#!/usr/bin/python
# -*- c         


        

Answer 1

As of today — June 2018

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PEP 263 itself mentions the regex it follows:

To define a source code encoding, a magic comment must be placed into the source files either as first or second line in the file, such as:

# coding=

or (using formats recognized by popular editors):

#!/usr/bin/python
# -*- coding:  -*-

or:

#!/usr/bin/python
# vim: set fileencoding= : 

More precisely, the first or second line must match the following regular expression:

^[ \t\f]*#.*?coding[:=][ \t]*([-_.a-zA-Z0-9]+)

So, as already summed up by other answers, it'll match coding with any prefix, but if you'd like to be as PEP-compliant as it gets (even though, as far as I can tell, using encoding instead of coding does not violate PEP 263 in any way) — stick with 'plain' coding, with no prefixes.