Where does this come from: -*- coding: utf-8 -*-

Question

Python recognizes the following as instruction which defines file's encoding:

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

I definitely saw this kind of instructions before (-*- var: value -*-). Where does it come from? What is the full specification, e.g. can the value include spaces, special symbols, newlines, even -*- itself?

My program will be writing plain text files and I'd like to include some metadata in them using this format.

Answer 1

In PyCharm, I'd leave it out. It turns off the UTF-8 indicator at the bottom with a warning that the encoding is hard-coded. Don't think you need the PyCharm comment mentioned above.

Answer 2

This way of specifying the encoding of a Python file comes from PEP 0263 - Defining Python Source Code Encodings.

It is also recognized by GNU Emacs (see Python Language Reference, 2.1.4 Encoding declarations), though I don't know if it was the first program to use that syntax.

Answer 3

This is so called file local variables, that are understood by Emacs and set correspondingly. See corresponding section in Emacs manual - you can define them either in header or in footer of file