Python configuration

Documentation

environment variables	https://docs.python.org/release/3.10.0/using/cmdline.html#environment-variables
compile options	https://docs.python.org/release/3.10.0/using/configure.html

Introspection

Version Info

import sys
print(sys.version_info)

python -V

Project Configuration

There are a few formats available to consolidate project dotfiles.
See helpful https://snarky.ca/what-the-heck-is-pyproject-toml/

python pyproject.toml	${PROJECT}/pyproject.toml	PEP-518
python setup.cfg	${PROJECT}/setup.cfg	PEP-390

Interpreter

Environment Variables

https://docs.python.org/release/3.10.0/using/cmdline.html#environment-variables

$PYTHONPATH	Where python looks for modules
$PYTHONSTARTUP	similar to .profile or .bashrc. Sets up interpreter environment
$PYTHONHOME	points to the root python directory. typically either /usr/lib/pythonX.X or C:/pythonX.X
$PYTHONWARNINGS=ignore	disable all warnings

Completion/Readline Support

Simply import the bulitin readline library to enable command completion and other readline features like vi mode.
You can do this automatically by configuring a pythonrc.

# ~/.pythonrc

try:
    import readline
except:
    pass

Startup

~/.local/lib/python2.7/site-packages/sitecustomize.py

modify startup

You can customize the python startup sequence (both interactive and noninteractive) by creating a custom sitecustomize.py file in your user_site directory. (which can be obtained with import site;print(site.USER_SITE) )

site-packages

You can add user-specific site-packages to a python install with the site module (with the advantage that *.pth files will be evaluated).

import site
site.add_sitedir('/tmp/my-site-dir')

Default Interpreter

Change the following registry-key in Windows. Alternatively, change the order that python appears on your $PATH variable.

HKLM\SOFTWARE\Python\PythonCore\2.7\InstallPath
  type: REG_SZ
  data: C:\Python2.7.3_x64\

Python Extensions

Python modules that require compiling must be compiled with the same compiler that python itself was built with. Microsoft distributes a minimalist compiler environment specifically for use with python/pip.

http://aka.ms/vcpython27