.. _configuring python:

####################
Python Configuration
####################


Setting the environment (python)
================================

To keep a consistent environment for python, the following are set:

- `PYTHONOPTIMIZE <https://docs.python.org/3/using/cmdline.html#envvar-PYTHONOPTIMIZE>`_
   0, When developing, exceptions, docstrings and breakpoints are wanted!

- `PYTHONUNBUFFERED <https://docs.python.org/3/using/cmdline.html#envvar-PYTHONUNBUFFERED>`_
   1, Reduce need to call *flush* and avoid headaches in general

- `PYTHONDONTWRITEBYTECODE <https://docs.python.org/3/using/cmdline.html#envvar-PYTHONDONTWRITEBYTECODE>`_
   1, Don't pollute the source tree with *__pycache__* directories

- `PYTHONHASHSEED <https://docs.python.org/3/using/cmdline.html#envvar-PYTHONHASHSEED>`_
   42, Reproducible hashes, if you have to ask why 42, hand in your geek badge!

- `PYTHONIOENCODING <https://docs.python.org/3/using/cmdline.html#envvar-PYTHONIOENCODING>`_
   utf8, Default to **UTF-8** encoding

- `PYTHONASYNCIODEBUG <https://docs.python.org/3/using/cmdline.html#envvar-PYTHONASYNCIODEBUG>`_
   1, Enable asynchronous debugging (required when developing  async components)

- `PYTHONDEVMODE <https://docs.python.org/3/using/cmdline.html#envvar-PYTHONDEVMODE>`_
   1, Toogle `sys.flags.dev_mode` attribute on
      and also enables extra run time checks
   
- `PYTHONUTF8 <https://docs.python.org/3/using/cmdline.html#envvar-PYTHONUTF8>`_
   1, Default file encoding

Configuration (bash)
====================

Define constants (bash)
-----------------------

Assuming :doc:`bash constants </requirements/system/bash/index>` has been followed:

.. code-block:: shell

   ~ $ printf "\\n# Developer environment (python)\\n\\n" >> $RC
   ~ $ printf "export PYTHONOPTIMIZE=0\n" >> $RC
   ~ $ printf "export PYTHONUNBUFFERED=1\n" >> $RC
   ~ $ printf "export PYTHONDONTWRITEBYTECODE=1\n" >> $RC
   ~ $ printf "export PYTHONHASHSEED=42\n" >> $RC
   ~ $ printf "export PYTHONIOENCODING=utf8\n" >> $RC
   ~ $ printf "export PYTHONASYNCIODEBUG=1\n" >> $RC
   ~ $ printf "export PYTHONUTF8=1\n" >> $RC
   ~ $ printf "export PYTHONDEVMODE=1\n" >> $RC

Define virtual environment root directory (PY_VENV_DIR)
-------------------------------------------------------

.. note::
   The following are optional

Define the root directory for all virtual environment installations.

.. code-block:: shell

   ~ $ printf "export PY_VENV_DIR=\$PREFIX/.share/virtualenvs\\n" >> $RC

**Congratulations, a python baseline environment is now defined!**