Pylons Related News for the 4th of July

It's been a busy month for Pylons, with lots of changes for the big internal API change in 0.9. The great news for those making Pylons apps right now with 0.8.2 is how few backwards compatibility issues there are. Most of the big changes take place under the hood and compatibility objects are present to mitigate the massive breakage that I've seen happen in other framework upgrades.

This is going to remain a big focus on future development in Pylons too, and the API in 0.9 is solid enough that I don't see anything but minor tweaks in the future (1.0 and beyond). Pylons based apps will be easy to maintain and upgrade thanks primarily to WSGI.

No NIH Syndrome Here

We've taken some cues from the Django project that we believe make for a cleaner request-cycle. In Pylons 0.9, controllers are expected to return a response object, and for convenience a method is included that renders a template to a new response object and returns it (This will look very familiar to Djangonauts).

The command was integrated with a slightly more enhanced version of Buffet along with the Beaker Session/Caching middleware. The end-result is a powerful command that not only can render templates in any Template-Plugin compatible template language, but the rendered result can also be cached. It's a great way to utilize template languages which might not be all that quick by themselves.

Sample controller in Pylons 0.9:

from myproj.lib.base import *

    class UserController(BaseController):
    def show(self, id):
        # Cache based on id in the URL, for 30 seconds
        return render_response('/user/show.myt', cache_key=id, cache_expire=30)

    def index(self):
        # Just for fun, use Kid to render the index
        return render_response('kid', 'user.index', cache_expire=15)

Being able to easily cache any template in any template language makes it very easy to sprinkle in caching when you need to handle massive loads yet stay dynamic.

Another new feature present in the latest Routes and Pylons is resource mappings, which automatically generate routes for you with HTTP method restrictions. This makes it easy to setup controllers and their actions for specific HTTP verbs (aka, REST-ful URL's and web services). The implementation of this feature was directly inspired by the Simply Restful Rails plug-in that was also demo'd by David Hansson in his Resources on Rails talk. Being able to discriminate valid routes based on HTTP method was brought up in the past and I'm happy to have seen an implementation that solves the issues I originally had with the idea.

The one feature still in development is to easily discern the content type requested, which was also inspired by Rails. Josh Triplett has written some code that deals with the ugly task of parsing the HTTP Accept headers, and I'm working on adding it into Paste for easy re-use by all. Combined with Routes, it'll provide a clean and easy way to setup web applications that can serve multiple forms of content from a single action.


Pylons was represented at EuroPython by the other lead developer of Pylons, James Gardner. For those still trying to grasp WSGI, he gave a talk on WSGI and middleware that looks like it was quite interesting (I wasn't there unfortunately.)

Other talks involving Pylons at EuroPython:

I'll be at OSCON for those interested in chatting about Pylons, Python, or Python web frameworks later this month.

Pylons 0.9 Release

We're currently wrapping up new features in 0.9, to make sure the resource mapping capability is present before a feature-freeze for release. Hopefully the release will be out within the next 2 weeks, if you haven't checked out Pylons before I'd highly suggest taking a look at 0.9!

Ben Bangert
Ben Bangert
Software Contriver

Code. Homebrew. Hike. Rollerblade.