Installing Python 3 on Mac OS X

Mac OS X comes with Python 2.7 out of the box.

You do not need to install or configure anything else to use Python 2. Theseinstructions document the installation of Python 3.

The version of Python that ships with OS X is great for learning, but it’s notgood for development. The version shipped with OS X may be out of date from theofficial current Python release,which is considered the stable production version.

Doing it Right

Let’s install a real version of Python.

Before installing Python, you’ll need to install GCC. GCC can be obtainedby downloading Xcode, the smallerCommand Line Tools (must have anApple account) or the even smaller OSX-GCC-Installerpackage.

Note

If you already have Xcode installed, do not install OSX-GCC-Installer.In combination, the software can cause issues that are difficult todiagnose.

Note

If you perform a fresh install of Xcode, you will also need to add thecommandline tools by running xcode-select —install on the terminal.

While OS X comes with a large number of Unix utilities, those familiar withLinux systems will notice one key component missing: a package manager.Homebrew fills this void.

To install Homebrew, open Terminal oryour favorite OS X terminal emulator and run

$ ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"

The script will explain what changes it will make and prompt you before theinstallation begins.Once you’ve installed Homebrew, insert the Homebrew directory at the topof your PATH environment variable. You can do this by adding the followingline at the bottom of your ~/.profile file

export PATH="/usr/local/opt/python/libexec/bin:$PATH"

If you have OS X 10.12 (Sierra) or older use this line instead

export PATH=/usr/local/bin:/usr/local/sbin:$PATH

Now, we can install Python 3:

$ brew install python

This will take a minute or two.

Pip

Homebrew installs pip pointing to the Homebrew’d Python 3 for you.

Working with Python 3

At this point, you have the system Python 2.7 available, potentially theHomebrew version of Python 2 installed, and the Homebrewversion of Python 3 as well.

$ python

will launch the Homebrew-installed Python 3 interpreter.

$ python2

will launch the Homebrew-installed Python 2 interpreter (if any).

$ python3

will launch the Homebrew-installed Python 3 interpreter.

If the Homebrew version of Python 2 is installed then pip2 will point to Python 2.If the Homebrew version of Python 3 is installed then pip will point to Python 3.

The rest of the guide will assume that python references Python 3.

# Do I have a Python 3 installed?
$ python --version
Python 3.7.1 # Success!

Pipenv & Virtual Environments

The next step is to install Pipenv, so you can install dependencies and manage virtual environments.

A Virtual Environment is a tool to keep the dependencies required by different projectsin separate places, by creating virtual Python environments for them. It solves the“Project X depends on version 1.x but, Project Y needs 4.x” dilemma, and keepsyour global site-packages directory clean and manageable.

For example, you can work on a project which requires Django 1.10 while alsomaintaining a project which requires Django 1.8.

So, onward! To the Pipenv & Virtual Environments docs!

This page is a remixed version of another guide,which is available under the same license.

原文: https://docs.python-guide.org/starting/install3/osx/