While other installation options are available, the easiest way to get started is with Homebrew:
$ brew install pyenv
🍺 /usr/local/Cellar/pyenv/1.2.10: 634 files, 2.4MB
Now let's install the latest Python version (3.7.3 as of this writing):
$ pyenv install 3.7.3
python-build: use openssl 1.0 from homebrew
python-build: use readline from homebrew
Downloading Python-3.7.3.tar.xz...
-> https://www.python.org/ftp/python/3.7.3/Python-3.7.3.tar.xz
Installing Python-3.7.3...
## further output not included ##
Now that Python 3 is installed through pyenv, we want to set it as our global default version for pyenv environments:
$ pyenv global 3.7.3
# and verify it worked
$ pyenv version 3.7.3
(set by /Users/Guest/.pyenv/version)
The power of pyenv comes from its control over our shell's path. In order for it to work correctly, we need to add the following to our configuration file (.zshrc for me, possibly .bash_profile for you):
$ echo -e 'if command -v pyenv 1>/dev/null 2>&1; then\n eval "$(pyenv init -)"\nfi' >> ~/.zshrc
We also need to remove the aliases we used in the sections above since they would prevent using pyenv correctly. After removing them, we can confirm pyenv is managing our Python 3 version:
# I start by resetting the current shell
$ exec $0
$ which python
/Users/Guest/.pyenv/shims/python
$ python -V
Python 3.7.3
$ pip -V
pip 19.0.3 from /Users/Guest/.pyenv/versions/3.7.3/lib/python3.7/site-packages/pip (python 3.7)
Now we know for certain that we're using Python 3.7.3 and pip will update alongside it without any manual aliasing between versions. Using Moshe's recommendation to use a version manager (pyenv) enables us to easily accept future upgrades without getting confused about which Python we are running at a given time.
