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Project Notes

Installing Python 2 and 3 on MacOS

Notes on installing and maintaining python 2 and 3 versions on MacOS.

Notes

macOS Sonoma

There is no python pre-installed with Sonoma 14.x. I’m no longer installing a python 2 version … so far no need; fingers crossed!

HomeBrew

Installing python with HomeBrew:

$ brew install python
$ brew info python
==> python@3.11: stable 3.11.6 (bottled)
Interpreted, interactive, object-oriented programming language
https://www.python.org/
/opt/homebrew/Cellar/python@3.11/3.11.6_1 (3,300 files, 62.2MB) *
  Poured from bottle using the formulae.brew.sh API on 2023-12-29 at 14:00:53
From: https://github.com/Homebrew/homebrew-core/blob/HEAD/Formula/p/python@3.11.rb
License: Python-2.0
==> Dependencies
Build: pkg-config ✘
Required: mpdecimal ✔, openssl@3 ✔, sqlite ✔, xz ✔
==> Caveats
Python has been installed as
  /opt/homebrew/bin/python3

Unversioned symlinks `python`, `python-config`, `pip` etc. pointing to
`python3`, `python3-config`, `pip3` etc., respectively, have been installed into
  /opt/homebrew/opt/python@3.11/libexec/bin

You can install Python packages with
  pip3 install <package>
They will install into the site-package directory
  /opt/homebrew/lib/python3.11/site-packages

tkinter is no longer included with this formula, but it is available separately:
  brew install python-tk@3.11

gdbm (`dbm.gnu`) is no longer included in this formula, but it is available separately:
  brew install python-gdbm@3.11
`dbm.ndbm` changed database backends in Homebrew Python 3.11.
If you need to read a database from a previous Homebrew Python created via `dbm.ndbm`,
you'll need to read your database using the older version of Homebrew Python and convert to another format.
`dbm` still defaults to `dbm.gnu` when it is installed.

For more information about Homebrew and Python, see: https://docs.brew.sh/Homebrew-and-Python
==> Analytics
install: 182,589 (30 days), 728,874 (90 days), 2,297,989 (365 days)
install-on-request: 121,915 (30 days), 443,490 (90 days), 1,229,628 (365 days)
build-error: 180 (30 days)

I’ve added unversioned python symlinks to the path:

export PATH="$PATH:/opt/homebrew/opt/python@3.11/libexec/bin"

Currently:

$ python --version
Python 3.11.6

Virtual Environments

With python 3, so much easier to create a virtual environment:

$ python -m venv venv
$ source venv/bin/activate
(venv) $

Earlier MacOS Versions

I didn’t make a note of which macOS version these earlier notes were made with. High Sierra? Definitely still on Intel processor.

HomeBrew

I’m using brew to install and upgrade system versions of python.

brew install python
brew install python3

Currently, the default python in my system is 2.7:

$ python --version
Python 2.7.16
$ which python
/usr/local/bin/python
$ which python3
/usr/local/bin/python3

Using VirtualEnv

To install virtualenv, it is now recommended to use pip user packages:

pip install --user virtualenv

NB: previously (and I think what I originally used on my machine) was to use easy_install sudo easy_install virtualenv.

Creating a python 3 virtual environment

$ virtualenv -p python3 venv3
$ source venv3/bin/activate
(venv3) $ python --version
Python 3.7.4
(venv3) $ deactivate

Creating a python 2 virtual environment

$ virtualenv venv
$ source venv/bin/activate
(venv) $ python --version
Python 2.7.16
(venv) $ deactivate

Credits and References

About LCK#203 python
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This page is a web-friendly rendering of my project notes shared in the LittleCodingKata GitHub repository.

LittleCodingKata is my collection of programming exercises, research and code toys broadly spanning things that relate to programming and software development (languages, frameworks and tools).

These range from the trivial to the complex and serious. Many are inspired by existing work and I'll note credits and references where applicable. The focus is quite scattered, as I variously work on things new and important in the moment, or go back to revisit things from the past.

This is primarily a personal collection for my own edification and learning, but anyone who stumbles by is welcome to borrow, steal or reference the work here. And if you spot errors or issues I'd really appreciate some feedback - create an issue, send me an email or even send a pull-request.