[python] What is the common header format of Python files?

I came across the following header format for Python source files in a document about Python coding guidelines:

#!/usr/bin/env python

"""Foobar.py: Description of what foobar does."""

__author__      = "Barack Obama"
__copyright__   = "Copyright 2009, Planet Earth"

Is this the standard format of headers in the Python world? What other fields/information can I put in the header? Python gurus share your guidelines for good Python source headers :-)

The answers above are really complete, but if you want a quick and dirty header to copy'n paste, use this:

#!/usr/bin/env python
# -*- coding: utf-8 -*-

"""Module documentation goes here
   and here
   and ...
"""

Why this is a good one:

• The first line is for *nix users. It will choose the Python interpreter in the user path, so will automatically choose the user preferred interpreter.
• The second one is the file encoding. Nowadays every file must have a encoding associated. UTF-8 will work everywhere. Just legacy projects would use other encoding.
• And a very simple documentation. It can fill multiple lines.

See also: https://www.python.org/dev/peps/pep-0263/

If you just write a class in each file, you don't even need the documentation (it would go inside the class doc).

I strongly favour minimal file headers, by which I mean just:

• The hashbang (#! line) if this is an executable script
• Module docstring
• Imports, grouped in the standard way, eg:

  import os    # standard library
  import sys

  import requests  # 3rd party packages

  from mypackage import (  # local source
      mymodule,
      myothermodule,
  )

ie. three groups of imports, with a single blank line between them. Within each group, imports are sorted. The final group, imports from local source, can either be absolute imports as shown, or explicit relative imports.

Everything else is a waste of time, visual space, and is actively misleading.

If you have legal disclaimers or licencing info, it goes into a separate file. It does not need to infect every source code file. Your copyright should be part of this. People should be able to find it in your LICENSE file, not random source code.

Metadata such as authorship and dates is already maintained by your source control. There is no need to add a less-detailed, erroneous, and out-of-date version of the same info in the file itself.

I don't believe there is any other data that everyone needs to put into all their source files. You may have some particular requirement to do so, but such things apply, by definition, only to you. They have no place in “general headers recommended for everyone”.

Also see PEP 263 if you are using a non-ascii characterset

Abstract

This PEP proposes to introduce a syntax to declare the encoding of a Python source file. The encoding information is then used by the Python parser to interpret the file using the given encoding. Most notably this enhances the interpretation of Unicode literals in the source code and makes it possible to write Unicode literals using e.g. UTF-8 directly in an Unicode aware editor.

Problem

In Python 2.1, Unicode literals can only be written using the Latin-1 based encoding "unicode-escape". This makes the programming environment rather unfriendly to Python users who live and work in non-Latin-1 locales such as many of the Asian countries. Programmers can write their 8-bit strings using the favorite encoding, but are bound to the "unicode-escape" encoding for Unicode literals.

Proposed Solution

I propose to make the Python source code encoding both visible and changeable on a per-source file basis by using a special comment at the top of the file to declare the encoding.

To make Python aware of this encoding declaration a number of concept changes are necessary with respect to the handling of Python source code data.

Defining the Encoding

Python will default to ASCII as standard encoding if no other encoding hints are given.

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=<encoding name>

or (using formats recognized by popular editors)

      #!/usr/bin/python
      # -*- coding: <encoding name> -*-

or

      #!/usr/bin/python
      # vim: set fileencoding=<encoding name> :

...