grammar.coffee (via). The annotated grammar for CoffeeScript, a new language that compiles to JavaScript developed by DocumentCloud’s Jeremy Ashkenas. The linked page is generated using Jeremy’s Docco tool for literate programming, also written in CoffeeScript. CoffeeScript itself is implemented in CoffeeScript, using a bootstrap compiler originally written in Ruby.

Scott and Scurvy. Did you know that Scott’s 1911 expedition to the south pole was plagued by scurvy, despite the British navy having discovered an effective cure way back in the 18th century? A fascinating tale of how scientific advances can lead to surprising regressions.

Announcing django-cachebot. The ORM caching space around Django is heating up. django-cachebot is used in production at mingle.com and takes a more low level approach to cache invalidation than Johnny Cache, enabling you to specifically mark the querysets you wish to cache and providing some advanced options for cache invalidation. Unfortunately it currently relies on a patch to Django core to enable its own manager.

How To Be A Good Participant On A Panel: Disagree. When I’m on a panel, I always try to have lunch or dinner with the other panelists beforehand to figure out in advance what points we disagree on.

Geospatial Indexing in MongoDB (via). New in version 1.3.3. Handles “order by distance from” queries using a geohash approach under the hood, automatically searching nearby grid squares until the correct number of results have been gathered. Bounding box search is planned for a future release.

Is johnny-cache for you?. “Using Johnny is really adopting a particular caching strategy. This strategy isn’t always a win; it can impact performance negatively”—but for a high percentage of Django sites there’s a very good chance it will be a net bonus.

Some People Can’t Read URLs. Commentary on the recent “facebook login” incident from Jono at Mozilla Labs. I’d guess that most people can’t read URLs, and it worries me more than any other aspect of today’s web. If you want to stay safe from phishing and other forms of online fraud you need at least a basic understanding of a bewildering array of technologies—URLs, paths, domains, subdomains, ports, DNS, SSL as well as fundamental concepts like browsers, web sites and web servers. Misunderstand any of those concepts and you’ll be an easy target for even the most basic phishing attempts. It almost makes me uncomfortable encouraging regular people to use the web because I know they’ll be at massive risk to online fraud.

Running Processes. I’ve been searching for a good solution to this problem (“run this program, and restart it if it falls over”) for years. I’m currently using god which works pretty well, but according to this article I should be learning upstart instead. It never ceases to amaze me how difficult this is, and how obtuse the tools are.

Internet Explorer: Global Variables, and Stack Overflows. An extremely subtle IE bug—if your recursive JavaScript function is attached directly to the window (global) object, IE won’t let you call it recursively more than 12 times.

GeoPlanet Explorer. Chris Heilmann’s YQL powered explorer for the invaluable Yahoo! GeoPlanet / WhereOnEarth dataset. Every API deserves an explorer of some sort.

jmoiron.net: Johnny Cache. The blog entry announcing Johnny Cache (“a drop-in caching library/framework for Django that will cache all of your querysets forever in a consistent and safe manner”) to the world.

Notes from a production MongoDB deployment. Notes from running MongoDB for 8 months in production, with 664 million documents spread across 72 GB master and slave servers located in two different data centers.

Node.js, redis, and resque (via). Paul Gross has been experimenting with Node.js proxies for allowing web applications to be upgraded without missing any requests. Here he places all incoming HTTP requests in a redis queue, then has his backend Rails servers consume requests from the queue and push the responses back on to a queue for Node to deliver. When the backend application is upgraded, requests remain in the queue and users see a few seconds of delay before their request is handled. It’s not production ready yet (POST requests aren’t handled, for example) but it’s a very interesting approach.

Johnny Cache. Clever twist on ORM-level caching for Django. Johnny Cache (great name) monkey-patches Django’s QuerySet classes and caches the result of every single SELECT query in memcached with an infinite expiry time. The cache key includes a “generation” ID for each dependent database table, and the generation is changed every single time a table is updated. For apps with infrequent writes, this strategy should work really well—but if a popular table is being updated constantly the cache will be all but useless. Impressively, the system is transaction-aware—cache entries created during a transaction are held in local memory and only pushed to memcached should the transaction complete successfully.

Unit Testing Achievements. A plugin for Python’s nose test runner that adds achievements—“Night Shift: Make a failing suite pass between 12am and 5am.”

ClearMaps: A Mapping Framework for Data Visualization. An open source library for map visualisations using ActionScript, with an Adobe AIR based encoding tool for translating data from shapefiles in to vector data suitable for use with the library.

kriszyp’s node-promise. Another elegant approach to managing asynchronous flows in Node, including running things both in parallel and serial.

Django Advent: Scaling Django. Mike Malone’s advice on scaling Django applications, including taking advantage of new features in 1.2.

PiCloud. An interesting twist on cloud computing for Python. “import cloud; cloud.call(my_function, arguments)” serialises my_function and its arguments, pushes it up to one of their EC2 servers and hands you back a job ID which you can poll (or block on) for a response. They suggest using it for long running tasks such as web crawling or image processing.

Internet Explorer Cookie Internals (FAQ). Grr... IE 6, 7 and 8 don’t support the max-age cookie argument, forcing you to use an explicit expiry date instead. This appears to affect the cache busting cookie pattern, where you set a cookie to expire in 30 seconds for any user who posts content and use the presence of that cookie to skip caches and/or send their queries to a master instead of slave database. If you have to use expires, users with incorrect system clocks may get inconsistent results. Anyone know of a workaround?

Using Bash’s History Effectively. The HISTIGNORE environment variable is particularly useful, allowing you to suppress certain commands by specifying a pattern. This article has a tip for causing a command to be omitted from the history if you prefix it with a space.

Hg Init. Joel Spolsky’s guide to Mercurial. If you’re still using a non-distributed version control system like Subversion, this is a great introduction to the new world order.

“Do” it fast!. Tim Caswell’s Do library has been upgraded for compatibility with Node v0.1.30, and now has a clever Do.convert() method which wraps Node’s low-level APIs with the Do libraries “continuable” abstraction.

node-v0.1.30 (via). A very significant new release of Node.js: the Twisted/Dojo-style Promise abstraction has been removed entirely, causing backwards incompatible changes to a bunch of core APIs. This means the pseudo-blocking Promise.wait() method is gone too, making it even harder to accidentally block your event loop. Instead, user-level libraries are encouraged to add Promise-style abstractions. I’m pleased to see Node sticking to the low-level stuff.

Ryan Tomayko on Github’s development process. In the comments—a fascinating insight in to how GitHub’s “developers work on whatever is most interesting to them” process manages to achieve really good results.

jacobian’s django-deployment-workshop. Notes and resources from Jacob’s 3 hour Django deployment workshop at PyCon, including example configuration files for Apache2 + mod_wsgi, nginx, PostgreSQL and pgpool.

Making Facebook 2x Faster. Facebook have a system called BigPipe which allows them to progressively send their pages to the browser as the server-side processing completes to optimise client loading time. Anyone reverse engineered this yet to figure out how they actually do it?