1,070 items tagged “python”
The Python programming language.
2010
Flask 0.1 Released. Armin’s Flask (a Python microframework built around Werkzeug and Jinja2) is looking pretty solid for a two week old project—extensive documentation, comprehensive unit test support (and example applications with unit tests) and some very tidy API design.
Introduction to Surlex. A neat drop-in alternative for Django’s regular expression based URL parsing, providing simpler syntax for common path patterns.
The Onion Uses Django, And Why It Matters To Us. The Onion ported their main site from PHP and Drupal to Django in three months with a team of four developers, including a full migration of their archived content. Their developers answer questions about the switch in this thread on the Django sub-reddit.
Fun with TextMate and PDB. TextMate bookmarks (against lines in a file) are stored as OS X extended attributes, which can be accessed from Python using the xattr module. Here’s a clever piece of code that uses bookmarks to set breakpoints in the command-line pdb debugger.
The Web Server Benchmarking We Need. Ian Bicking asks for a WSGI benchmark which emphasises error handling over raw performance—can the server keep serving requests if some of them are CPU bound, I/O bound, wedged or cause a segfault?
Automated deployments with Fabric—tips and tricks. “If it’s not in a Fabric fabfile, it’s not deployable”—I’m slowly applying this philosophy to my personal projects.
Installing PIL on Mac OS X Snow Leopard for use in Google App Engine. PIL installation instructions that actually work... the ’export CC=“gcc -arch i386”’ incantation in particular. Make sure you run setup.py install using the Python version that the App Engine dev tools are using (I ran “sudo /usr/bin/python2.6 setup.py install”).
Introducing the PyPy 1.2 release. It’s been a long time coming, but 1.2 is the first PyPy release to ship with a Just-in-Time compiler! Performance looks pretty impressive.
Cache Machine: Automatic caching for your Django models. This is the third new ORM caching layer for Django I’ve seen in the past month! Cache Machine was developed for zamboni, the port of addons.mozilla.org to Django. Caching is enabled using a model mixin class (to hook up some post_delete hooks) and a custom caching manager. Invalidation works by maintaining a “flush list” of dependent cache entries for each object—this is currently stored in memcached and hence has potential race conditions, but a comment in the source code suggests that this could be solved by moving to redis.
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.
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.
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.”
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.
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.
Why toppcloud will not be agnostic. Ian Bicking’s toppcloud aims to offer deployment with the ease of use of AppEngine against a standard, open source Ubuntu + Python 2.6 + mod_wsgi + Varnish stack. Here he explains why he’s not going to vary the required components: keeping everything completely standardised means everyone gets the same bugs (and the same fixes).
Presenting django-devserver, a better runserver. I really like this—it’s a Django management command (./manage.py rundevserver) which adds SQL logging and cache access summaries to the console output of Django’s local development server. It solves a similar set of problems to the debug toolbar, but requires slightly less setup and doesn’t inject additional HTML in to your pages. You can add your own custom modules to it as well.
Integrate Tornado in Django. A handy ./manage.py runtornado management command for firing up a Tornado server that serves your Django application.
What’s hot? Introducing Zeitgeist. Dan Catt’s first project at the Guardian. “When something appears on the Zeitgeist page, it’s because it performed better (got more attention) than the norm for that content type/section/day”. The application itself is written in Python and runs on Google App Engine.
Distributed lock on top of memcached. A simple Python context manager (taking advantage of the with statement) that implements a distributed lock using memcached to store lock state: “memcached_lock can be used to ensure that some global data is only updated by one server”. Redis would work well for this kind of thing as well.
Introducing docent. Paul Mison’s clever little Flickr app for viewing galleries that have been added by your contacts. It runs in Python on App Engine and makes extensive use of the Task Queue API.
Reexamining Python 3 Text I/O. Python 3.1’s IO performance is a huge improvement over 3.0, but still considerably slower than 2.6. It turns out it’s all to do with Python 3’s unicode support: When you read a file in to a string, you’re asking Python to decode the bytes in to UTF-8 (the new default encoding) at the same time. If you open the file in binary mode Python 3 will read raw bytes in to a bytestring instead, avoiding the conversion overhead and performing only 4% slower than the equivalent code in Python 2.6.4.
World Government Data. Launched last week, this is the Guardian’s meta-search engine for searching and browsing through data from four different government data sites (with more sites planned). Under the hood it’s Django, Solr, Haystack and the Scrapy crawling library. The application was built by Ben Firshman during an internship over Christmas.
For the Love of Ponies. Bryan Veloso, the discoverer of the Django Pony, makes contact with the artist who released the original drawing on iStockPhoto.
WildlifeNearYou: It began on a fort...
Back in October 2008, myself and 11 others set out on the first /dev/fort expedition. The idea was simple: gather a dozen geeks, rent a fort, take food and laptops and see what we could build in a week.
[... 558 words]What’s new in Django 1.2 alpha 1 (via) Multiple database support, improved CSRF prevention, a messages framework (similar to the Rails “flash” feature), model validation, custom e-mail backends, template caching for much faster handling of the include and extends tags, read only fields in the admin, a better if tag and more. Very exciting release.
last.fm for television. Dale Lane’s neat hack to visualise his television watching habits. An Ubuntu / vdx home theatre stores TV events in SQLite, and graphs are generated using Python and Open Flash Chart 2. The really clever bit: the back-end captures nearby bluetooth IDs’ allowing events to be filtered by the people watching based on the presence of their mobile phones.
Current State of Unladen Swallow (Towards a Faster Python). The Unladen Swallow team are now planning to merge their work back in to the mainline Python 3 branch, adding a powerful incentive for Python developers to port their old Python 2 code (since the official Python 2.x line is extremely unlikely to have Unladen Swallow merged in to it).
rlisagor’s freshen. A Python clone of Ruby’s innovative Cucumber testing framework. Tests are defined as a set of plain-text scenarios, which are then executed by being matched against test functions decorated with regular expressions. Has anyone used this or Cucumber? I’m intrigued but unconvinced—are the plain text scenarios really a useful way of defining tests?
Timing attack in Google Keyczar library. An issue I also need to fix in the proposed Django signing code. If you’re comparing two strings in crypto (e.g. seeing if the provided signature matches the expected signature) you need to use a timing independent string comparison function or you risk leaking information. This kind of thing is exactly why I want an audited signing module in Django rather than leaving developers to figure it out on their own.