Python Setup

As the world of Python starts to get more traction with Python 3, important technologies such as Pyramid need to work harder to not just tolerate Python 3 but to embrace it. As a step towards this, our Getting Started tutorial features Python 3.3+ (though it will also work as-is in Python 2.)

This, of course, introduces some complexity.

Python 3.3 From Source

Compiling and installing your own Python 3 or 2 is always the preferred solution. As this document later shows, issues arise from using pre-packaged installations.

First:

1. Download and compile Python from source
2. Install it to a directory of your choosing

Below, path/to/python/bin refers to this directory.

Making a Virtual Environment

Developing in isolation helps us ensure what we are learning doesn’t conflict with any packages installed from other work on the machine. Virtual environments let us do just this.

Python 3.3 has support for virtual environments using the pyvenv command. Since we are embracing Python 3.3, let’s use its virtualenv approach.

$ path/to/python/bin/pyvenv-3.3 env33
$ source env33/bin/activate
(env33)$ which python3.3

Once you do this, your path will be setup to point at the bin of your virtual environment. Your prompt will also change, as noted above.

Note

If you are an OS X user that got your Python 3.3 from Homebrew, its pyvenv is broken (as of Feb 2013.) If you still want to use Homebrew, do pip install virtualenv and make your virtual environments with virtualenv.

Note

If you are a Windows user that got your Python 3.3 from python.org, there’s no pyvenv-3.3 script and there’s no .exe wrapper for pyvenv script. Instead of using pyvenv directly you should either use path\to\python\python.exe path\to\python\Tools\Scripts\pyvenv.py or path\to\python\python.exe -m venv instead. See http://stackoverflow.com/q/15981111/95735 for more details.

Installing Packaging Tools

Almost there. pyvenv doesn’t copy any of the Python packaging tools into your virtualenv. Fortunately this is easy and supported: just download and install distribute.

(env33)$ curl -O http://python-distribute.org/distribute_setup.py
(env33)$ python3.3 distribute_setup.py

Note

Make sure the python3.3 above is from your virtualenv!