With all of the exciting updates to Mercurial recently, I've been on a rampage, updating various boxes everywhere I go. I'm in the habit of using easy_install and/or pip to install most of my Python-related packages. It's pretty easy to install packages that are in well-known locations (like PyPI or on Google Code, for example). It's also pretty easy to update packages using either utility. Both take a -U parameter, which, to my knowledge, tells it to actually check for updates and install the latest version.

That's all fine and dandy, but what happens when you want to install an "unofficial" version of some package? I mean, what if your favorite project all of the sudden includes some feature that you will die unless you can have access to it and the next official version is weeks or months in the future? There are typically a few avenues you can take to satisfy your needs, but I wanted to bring up something that I think not many people are aware of: easy_install and pip can both understand URLs to installable Python packages.

What do I mean by that, you ask? Well, when you get down to the basics of what both utilities do, they just take care of downloading some Python package and installing it with the setup.py file contained therein. In many cases, these utilities will search various package repositories, such as PyPI, to download whatever package you specify. If the package is found, it will be downloaded and extracted.

In most cases, you can do all of that yourself:

$ wget http://pypi.python.org/someproject/somepackage.tar.gz
$ tar zxf somepackage.tar.gz
$ cd somepackage
$ python setup.py install

Both easy_install and pip obviously do a lot of other magic, but that is perhaps the most basic way to understand what they do. To answer that last question, you can help your utility of choice out by specifying the exact URL to the specific package you want it to install for you:

$ easy_install http://pypi.python.org/someproject/somepackage.tar.gz
$ pip install http://pypi.python.org/someproject/somepackage.tar.gz

For me, this feature comes in very handy with projects that are hosted on BitBucket, for example, because you can always get any revision of the project in a tidy .tar.gz file. So when I'm updating Mercurial installations, I can do this to get the latest stable revision:

$ easy_install http://selenic.com/repo/hg-stable/archive/tip.tar.gz

It's pretty slick. Here's a full example:

[user@web ~]$ hg version
Mercurial Distributed SCM (version 1.2.1)

Copyright (C) 2005-2009 Matt Mackall <mpm@selenic.com> and others
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
[user@web ~]$ easy_install http://selenic.com/repo/hg-stable/archive/tip.tar.gz
Downloading http://selenic.com/repo/hg-stable/archive/tip.tar.gz
Processing tip.tar.gz
Running Mercurial-stable-branch--8bce1e0d2801/setup.py -q bdist_egg --dist-dir /tmp/easy_install-Gnk2c9/Mercurial-stable-branch--8bce1e0d2801/egg-dist-tmp--2VAce
zip_safe flag not set; analyzing archive contents...
mercurial.help: module references __file__
mercurial.templater: module references __file__
mercurial.extensions: module references __file__
mercurial.i18n: module references __file__
mercurial.lsprof: module references __file__
Removing mercurial unknown from easy-install.pth file
Adding mercurial 1.4.1-4-8bce1e0d2801 to easy-install.pth file
Installing hg script to /home/user/bin

Installed /home/user/lib/python2.5/mercurial-1.4.1_4_8bce1e0d2801-py2.5-linux-i686.egg
Processing dependencies for mercurial==1.4.1-4-8bce1e0d2801
Finished processing dependencies for mercurial==1.4.1-4-8bce1e0d2801
[user@web ~]$ hg version
Mercurial Distributed SCM (version 1.4.1+4-8bce1e0d2801)

Copyright (C) 2005-2009 Matt Mackall <mpm@selenic.com> and others
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Notice the version change from 1.2.1 to 1.4.1+4-8bce1e0d2801. w00t.

Edit: devov pointed out that pip is capable of installing packages directly from its repository. I've never used this functionality, but I'm interested in trying it out sometime! Thanks devov!

Today I found myself trying to figure out how to make a terminal window stay permanent on my desktop or dashboard on OSX, similar to what I've done in the past with Linux. I just wanted to have the terminal window monitoring things in the background for me. Actually, all I wanted to do was keep track of when my local working copy of our Subversion repository was out of sync. I wanted a solution that would keep out of my way, but I also wanted it to be easy.

My search for a solution seemed short-lived when a Google search suggested a dashboard widget for the Terminal application. The problem with it was that the download server was dead or simply blocked by my company's Internet filter. One way or another, it wasn't long before I went in search of another solution.

At that very instant, I received a Growl notification from some program. That's when it dawned on me--I could tell Growl to tell me when my working copy was out of sync. I had done stuff like that in the past, so I set out to write my solution. This is what I came up with:

#!/bin/bash
MY_BOX=[my IP address]
DEV_ROOT='/path/to/svn/working copy'
cd $DEV_ROOT

MY_REV=`svn log --limit 1 | awk '/^r/ {print $1}' | sed 's/[^0-9]//g'`
SVN_REV=`svn log --limit 1 -r HEAD | awk '/^r/ {print $1}' | sed 's/[^0-9]//g'`

if [[ $MY_REV != $SVN_REV ]]; then
    ssh username@$MY_BOX "growlnotify -s -d47111 -n 'iTerm' -t 'Out Of Sync' -m 'Your working copy is out of sync.  Repository is at revision $SVN_REV, and your working copy is at $MY_REV.'"
fi

Now, a little bit about my environment. As I've mentioned before, all of our development really takes place on Linux-powered virtual machines. We simply use our Macs as the system to interact with those virtual machines. That is why there's the ssh line in that script.

Basically, this script just checks the most recent revision in your local working copy. Then it checks the latest revision in the repository itself. It compares the two revision numbers, and if it finds a difference, it will SSH into my OSX box to send me a Growl notification. On the OSX side, I have Growl and growlnotify installed. Here's a summary of the options to growlnotify:

• -s: make the notification sticky--don't hide the notification until the user specifically closes it.
• -d47111: a unique identifier for the notification. This makes it so you can send the same message over and over and it would update any existing notifications with that ID instead of creating a new notification (unless one doesn't exist already).
• -n 'iTerm': I believe this was supposed to be the "source" application. I don't remember right now.
• -t 'Out Of Sync': The title for the notification.
• -m 'Your working copy...': The message to send to my Mac.

This is a fabulous little reminder to me. I have it set up as a cronjob that runs every minute on my Linux-powered development virtual machine. Hopefully this will help others!

Last night I noticed that Google Code is actually offering the Mercurial project hosting that they promised back in April. I guess it's been around for most of May, but I never saw any news to suggest that it was actually public. As soon as I noticed it, I converted one of my less-known, less-used SVN projects to Mercurial. I'm really liking it.

I need to do a bit more work on this particular project before I announce it to the world, but it's out there, and it's Mercurial powered now babay. I think I will be leaving most of my other projects in SVN so I don't upset all of the other people who actually use them.

Oh, I also noticed that the project quotas were bumped up quite a bit. Now each project seems to get a whopping 1GB of space for free!!! What do you have to say about that, BitBucket/GitHub/Assembla/[insert dirty, rotten free open source project hosting host name here]?!

Hooray for Google Code!