5. Using Python on a Mac

Autor:

Bob Savage <bobsavage@mac.com>

Python on a Mac running macOS is in principle very similar to Python on any other Unix platform, but there are a number of additional features such as the integrated development environment (IDE) and the Package Manager that are worth pointing out.

5.1. Getting and Installing Python

macOS used to come with Python 2.7 pre-installed between versions 10.8 and 12.3. You are invited to install the most recent version of Python 3 from the Python website. A current „universal2 binary” build of Python, which runs natively on the Mac’s new Apple Silicon and legacy Intel processors, is available there.

What you get after installing is a number of things:

  • A Python 3.12 folder in your Applications folder. In here you find IDLE, the development environment that is a standard part of official Python distributions; and Python Launcher, which handles double-clicking Python scripts from the Finder.

  • A framework /Library/Frameworks/Python.framework, which includes the Python executable and libraries. The installer adds this location to your shell path. To uninstall Python, you can remove these three things. A symlink to the Python executable is placed in /usr/local/bin/.

Informacja

On macOS 10.8-12.3, the Apple-provided build of Python is installed in /System/Library/Frameworks/Python.framework and /usr/bin/python, respectively. You should never modify or delete these, as they are Apple-controlled and are used by Apple- or third-party software. Remember that if you choose to install a newer Python version from python.org, you will have two different but functional Python installations on your computer, so it will be important that your paths and usages are consistent with what you want to do.

IDLE includes a Help menu that allows you to access Python documentation. If you are completely new to Python you should start reading the tutorial introduction in that document.

If you are familiar with Python on other Unix platforms you should read the section on running Python scripts from the Unix shell.

5.1.1. How to run a Python script

Your best way to get started with Python on macOS is through the IDLE integrated development environment; see section The IDE and use the Help menu when the IDE is running.

If you want to run Python scripts from the Terminal window command line or from the Finder you first need an editor to create your script. macOS comes with a number of standard Unix command line editors, vim nano among them. If you want a more Mac-like editor, BBEdit from Bare Bones Software (see https://www.barebones.com/products/bbedit/index.html) are good choices, as is TextMate (see https://macromates.com). Other editors include MacVim (https://macvim.org) and Aquamacs (https://aquamacs.org).

To run your script from the Terminal window you must make sure that /usr/local/bin is in your shell search path.

To run your script from the Finder you have two options:

  • Drag it to Python Launcher.

  • Select Python Launcher as the default application to open your script (or any .py script) through the finder Info window and double-click it. Python Launcher has various preferences to control how your script is launched. Option-dragging allows you to change these for one invocation, or use its Preferences menu to change things globally.

5.1.2. Running scripts with a GUI

With older versions of Python, there is one macOS quirk that you need to be aware of: programs that talk to the Aqua window manager (in other words, anything that has a GUI) need to be run in a special way. Use pythonw instead of python to start such scripts.

With Python 3.9, you can use either python or pythonw.

5.1.3. Configuration

Python on macOS honors all standard Unix environment variables such as PYTHONPATH, but setting these variables for programs started from the Finder is non-standard as the Finder does not read your .profile or .cshrc at startup. You need to create a file ~/.MacOSX/environment.plist. See Apple’s Technical Q&A QA1067 for details.

For more information on installation Python packages, see section Installing Additional Python Packages.

5.2. The IDE

Python ships with the standard IDLE development environment. A good introduction to using IDLE can be found at https://www.hashcollision.org/hkn/python/idle_intro/index.html.

5.3. Installing Additional Python Packages

This section has moved to the Python Packaging User Guide.

5.4. GUI Programming

There are several options for building GUI applications on the Mac with Python.

PyObjC is a Python binding to Apple’s Objective-C/Cocoa framework, which is the foundation of most modern Mac development. Information on PyObjC is available from https://pypi.org/project/pyobjc/.

The standard Python GUI toolkit is tkinter, based on the cross-platform Tk toolkit (https://www.tcl.tk). An Aqua-native version of Tk is bundled with macOS by Apple, and the latest version can be downloaded and installed from https://www.activestate.com; it can also be built from source.

A number of alternative macOS GUI toolkits are available:

  • PySide: Official Python bindings to the Qt GUI toolkit.

  • PyQt: Alternative Python bindings to Qt.

  • Kivy: A cross-platform GUI toolkit that supports desktop and mobile platforms.

  • Toga: Part of the BeeWare Project; supports desktop, mobile, web and console apps.

  • wxPython: A cross-platform toolkit that supports desktop operating systems.

5.5. Distributing Python Applications

A range of tools exist for converting your Python code into a standalone distributable application:

  • py2app: Supports creating macOS .app bundles from a Python project.

  • Briefcase: Part of the BeeWare Project; a cross-platform packaging tool that supports creation of .app bundles on macOS, as well as managing signing and notarization.

  • PyInstaller: A cross-platform packaging tool that creates a single file or folder as a distributable artifact.

5.6. Other Resources

The Pythonmac-SIG mailing list is an excellent support resource for Python users and developers on the Mac:

https://www.python.org/community/sigs/current/pythonmac-sig/

Another useful resource is the MacPython wiki:

https://wiki.python.org/moin/MacPython