Python OS X 10.5 development environment

Question

I would like to try out the Google App Engine Python environment, which the docs say runs 2.5.2. As I use OS X Leopard, I have Python 2.5.1 installed, but would like the latest

Answer 1

You can install python on your Mac, and it won't mess with the default installation. However, I strongly recommend that you use MacPorts to install Python, since that will make it much easier for you to install Python libraries and packages further down the road. Additionally, if you try to install a program or library with MacPorts that depends on Python, MacPorts will download a copy of Python, even if you have MacPython installed, so you might end up with redundant copies of Python if you install MacPython but then choose to use MacPorts at a later date. To install Python with MacPorts, download and install MacPorts, then type:

sudo port install python25 python_select
sudo python_select python25

Run the following command to view all the MacPorts packages for Python:

port list | grep py25-

You can install any of the packages on the list by simply typing:

sudo port install packagename

In the above, replace packagename with the name of the package. On my first install I always run

sudo port install py25-setuptools

[ NOTE: These commands need to be run from the Terminal -- Applications > Utilities > Terminal.app ]

Answer 2

Your current python is in /System/Library/Frameworks/Python.framework/.

If you install MacPython, it will go into /Library/Frameworks/Python.framework/. The installer will modify your $PATH (environment variable) so that typing python at the command line will run the version it installs.

You can easily get back the old version by modifying the path again.

You will have to reinstall any third-party modules you are using. This is because third-party modules go into Python.framework/Versions/Current/lib/python2.5/site-packages/ for the version you're running.

Since you're not modifying the system version, you aren't in danger of affecting any Apple system tools that rely on it.

(in fact, arguably it is safer to install MacPython from the start, and never touch the Apple-supplied version. See here for a similar situation involving Perl, where Apple updated the version of Perl in /System and broke a lot of people's setups)

You may also be interested in virtualenv.