Homebrew and Python

Note: This page describes Homebrew's Python formula as it will be after this Issue is resolved: https://github.com/mxcl/homebrew/issues/4226

work-in-progress

• site-packages
• scripts folder
• distutils.cfg

Overview

Homebrew provides a formula for Python 2.7.1. This is somewhat counter to the "no system duplicates" policy, but

Issues

Assuming a standard Homebrew install, the Prefix will be /usr/local and the Cellar will be /usr/local/Cellar.

Homebrew installs Python to the Cellar, using the standard ./configure --prefix=#{prefix}.

This sets up:

• the "site-packages" folder as /usr/local/Cellar/python/2.7.1/lib/python2.7/site-packages.
• the "install-scripts" folder as /usr/local/Cellar/python/2.7.1/bin.

If site-packages lives in Python's Cellar, then user installed packages will be wiped between Python updates. Same for install-scripts, with the added problem that users have to manually add Python's cellar bin folder to the path.

Solution

Homebrew performs two actions on install to address these issues.

First, the Cellar site-packages folder is removed, and a symlink to /usr/local/lib/python2.7/site-packages in the Prefix is created. This will allow site-packages to persist between Python updates, as Homebrew has special handling for some languages that use lib for user-installable libraries.

Second, a distutils.cfg file is written ( http://docs.python.org/install/index.html#distutils-configuration-files ) to set the install-scripts folder to /usr/local/share/python. Users can add /usr/local/share/python to the PATH to pick up installed scripts.

These changes allow Homebrew to play along with distutils, which is the basis for distribute and pip as well.

Because of these changes, the separate distribute and pip formulae are no longer needed, and have been removed.

Distribute, Pip, etc.

Assuming the Python brew installs Distribute, does this work?

• distribute provides easy_install in /usr/local/share/python.
• easy_install pip to get pip
• pip install --upgrade distribute to update distribute