python

Yesterday, virtualenv-burrito 2.7 was released. There are two significant changes:

1. All Python packages in the .venvburrito directory are now inside a versioned site-packages directory. For example, if you are running Python 2.7 during the install or upgrade, all packages will now live in lib/python2.7/site-packages.
2. The pip program is no longer user accessible (i.e., in the PATH). You could easily figure out where it’s been moved, but that’s discouraged (and unsupported).

A simple way for Python cron tasks to exit if another process is currently running. Does not use a pidfile.

import os
import subprocess
import shlex


def bail_if_another_is_running():
    cmd = shlex.split("pgrep -u {} -f {}".format(os.getuid(), __file__))
    pids = subprocess.check_output(cmd).strip().split('\n')
    if len(pids) > 1:
        pids.remove("{}".format(os.getpid()))
        print "Exiting! Found {} is already running (pids): {}".format(
            __file__, " ".join(pids))
        raise SystemExit(1)

Update 2011-09-27: Turns out virtualenv and virtualenvwrapper support this out of the box. Most of what’s written below is horrifically complex compared to just using the -p switch when you make your virtualenv. You simply need to do this:

mkvirtualenv -p /path/to/some/python coolname

That’ll create a new virtualenv called “coolname” that uses /path/to/some/python for it’s Python interpreter. I’ve tested this with PyPy and it worked great.

This Python breakfast just got tastier. A major update to the way Virtualenv Burrito works was released this weekend. There is now full support for extension points and a less hackish way of managing the packages¹ under the hood.

Over the weekend I finished¹ a tool called Virtualenv Burrito. It’s goal was to be a single command which would setup Virtualenv and Virtualenvwrapper so you could start hacking on Python projects as quickly as possible. As a bonus, it installs the virtualenv-burrito command which will upgrade those packages to the latest versions I’ve tested.

During Steve Huffman’s and Alexis Ohanian’s Pycon Keynote, someone asked why Reddit was moved from Lisp to Python. The reason for moving wasn’t too interesting, but why they have stayed is. Steve gave two “huge” reasons Reddit continues to use Python: