Python 官方最新版本、Homebrew 版本和安装版本在 macOS 上有所不同

Question

1. According to python.org , 3.8.2 is currently the latest version of Python.
2. When I try to upgrade python3 using Homebrew (freshly upgraded), it tells me version 3.7.6_1 is already installed.
3. When I ask python3 for it's current version, it tells me 3.7.3.

See terminal runs:

Nannas-Computer:some_folder username$ brew update
Already up-to-date.
Nannas-Computer:some_folder username$ brew upgrade
Nannas-Computer:some_folder username$ brew upgrade python3
Warning: python3 3.7.6_1 already installed
Nannas-Computer:some_folder username$ python3 --version
Python 3.7.3

Why are all these versions different, and how can I install the 3.8.2 version on my mac (macOS Mojave, version 10.14.6)?

Answer 1

You can install Python 3.8.x using command:

brew install python@3.8

As it's not main Python distribution on Homebrew, by default it's not accessible by simple typing python3 . Binary is located in /usr/local/Cellar/python@3.8/3.8.2/bin/python3.8 and you can create a symlink to it or use directly by typing full path.

It's not that cumbersome as one may think because usually the only thing you need to do is to create a virtual environment and activate it. Since then it'll be your default Python (for this virtualenv):

$ /usr/local/Cellar/python@3.8/3.8.1/bin/python3.8 -m venv my_venv
$ source my_venv/bin/activate
(my_venv)$ python
Python 3.8.1 (default, Dec 27 2019, 18:06:00)
[Clang 11.0.0 (clang-1100.0.33.16)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>>

Answer 2

After some research I found out the following reasons:

• It is possible to upgrade to Python 3.8.2 via Homebrew, but it isn't listed as supplying python due to some complications. See status here . Until this issue is done, 3.7.6_1 is the newest version you can upgrade to (as Homebrew kept telling me).

• When I ran python3 --version in terminal, it returned Python 3.7.3 because I had installed this version myself at some point from the official website, without using Homebrew. Upgrading python to 3.7.6 via Homebrew had no effect on this dominating installation of python. I got rid of the manually installed version using this useful answer, after which I reinstalled python properly using Homebrew just to be on the safe side and now I finally have:

   Nannas-Computer:some_folder username $ python3 --version Python 3.7.6