Python Enhancement Proposals
============================

.. image:: https://travis-ci.org/python/peps.svg?branch=master
    :target: https://travis-ci.org/python/peps

The PEPs in this repo are published automatically on the web at
https://www.python.org/dev/peps/.  To learn more about the purpose of
PEPs and how to go about writing a PEP, please start reading at PEP 1
(``pep-0001.txt`` in this repo).  Note that PEP 0, the index PEP, is
now automatically generated, and not committed to the repo.


Contributing to PEPs
====================

See the `Contributing Guidelines <./CONTRIBUTING.rst>`_.


reStructuredText for PEPs
=========================

Original PEP source should be written in reStructuredText format,
which is a constrained version of plaintext, and is described in
PEP 12.  Older PEPs were often written in a more mildly restricted
plaintext format, as described in PEP 9.  The ``pep2html.py``
processing and installation script knows how to produce the HTML
for either PEP format.

For processing reStructuredText format PEPs, you need the docutils
package, which is available from `PyPI <https://pypi.org/>`_.
If you have pip, ``pip install docutils`` should install it.


Generating the PEP Index
========================

PEP 0 is automatically generated based on the metadata headers in other
PEPs. The script handling this is ``genpepindex.py``, with supporting
libraries in the ``pep0`` directory.


Checking PEP formatting and rendering
=====================================

Do not commit changes with bad formatting.  To check the formatting of
a PEP, use the Makefile.  In particular, to generate HTML for PEP 9999,
your source code should be in ``pep-9999.rst`` and the HTML will be
generated to ``pep-9999.html`` by the command ``make pep-9999.html``.
The default Make target generates HTML for all PEPs.

If you don't have Make, use the ``pep2html.py`` script directly.


Generating HTML for python.org
==============================

python.org includes its own helper modules to render PEPs as HTML, with
suitable links back to the source pages in the version control repository.

These can be found at https://github.com/python/pythondotorg/tree/master/peps

When making changes to the PEP management process that may impact python.org's
rendering pipeline:

* Clone the python.org repository from https://github.com/python/pythondotorg/
* Get set up for local python.org development as per
  https://pythondotorg.readthedocs.io/install.html#manual-setup
* Adjust ``PEP_REPO_PATH`` in ``pydotorg/settings/local.py`` to refer to your
  local clone of the PEP repository
* Run ``./manage.py generate_pep_pages`` as described in
  https://pythondotorg.readthedocs.io/pep_generation.html


Rendering PEPs with Sphinx
==========================

There is a Sphinx-rendered version of the PEPs at https://python.github.io/peps/
(updated on every push to ``master``)

**Warning:** This version is not, and should not be taken to be, a canonical
source for PEPs whilst it remains in preview (`please report any rendering bugs
<https://github.com/python/peps/issues/new>`_). The canonical source for PEPs remains
https://www.python.org/dev/peps/

Build PEPs with Sphinx locally:
-------------------------------

1. Ensure you have Python >=3.9 and Sphinx installed
2. If you have access to ``make``, follow (i), otherwise (ii)

   i.  Run ``make sphinx-local``
   ii. Run ``python build.py -j 8 --build-files``. Note that the jobs argument
       only takes effect on unix (non-mac) systems.
3. Wait for Sphinx to render the PEPs. There may be a series of warnings about
   unreferenced citations or labels -- whilst these are valid warnings they do
   not impact the build process.
4. Navigate to the ``build`` directory of your PEPs repo to find the HTML pages.
   PEP 0 provides a formatted index, and may be a useful reference.

Arguments to ``build.py``:
--------------------------

Renderers:

``-f`` or ``--build-files``
    Renders PEPs to ``pep-XXXX.html`` files

``-d`` or ``--build-dirs``
    Renders PEPs to ``index.html`` files within ``pep-XXXX`` directories

Options:

``-i`` or ``--index-file``
    Copies PEP 0 to a base index file

``-j`` or ``--jobs``
    How many parallel jobs to run (if supported). Integer, default 1

``-n`` or ``--nitpicky``
    Runs Sphinx in `nitpicky` mode

``-w`` or ``--fail-on-warning``
    Fails Sphinx on warnings

Tools:

``-l`` or ``--check-links``
    Checks validity of links within PEP sources