Porting Django apps to Python 3¶
Django 1.5 now supports Python 3, so now’s the time to start thinking about porting your apps and sites. Come see how! I’ll talk about the porting techniques that work, and present two case studies: porting a site, and porting a reusable app.
by Jacob Kaplan-Moss
- Django co-creator and BDFL
- https://github.com/jacobian / https://twitter.com/jacobian
Do I want to use Python 3?¶
Python 3 has fewer warts
urllib/ urllib2 replaced with urlparse- std library cleanup
- funky syntax is killed
- print() is a function!
- super() syntax is better!
- unicode no longer sucks!
Can I use Python 3?¶
A solid maybe. Missing pieces as of 3/16/2013:
No Python Image Library (PIL / Pillow)
No MySQL python 3 bindings aren’t that good.
Popular items on https://www.djangopackages.com:
- No gunicorn as async (sync does work)
- No django-debug-toolbar
- No django-registration
- No django-extensions
- No Haystack
- No django-tagging
- No Sentry
- No django-compressor
Much easier for new projects over existing sites
Options¶
Python 3 only
- Brand new project
- Fewer dependencies
Translated source (2to3)
Single codebase
3 only¶
Good for new Django sites.
2to3¶
First tool released for maintaining code, lets you translate from Python 2 to Python 3.
It’s amazing but not that practical: if you release the Python 3 version of code generated by 2to3 and then someone sends you a Python 3 patch, you have to port the patch to 2, apply it, and run 2to3.
How to port to Python 3¶
Choose an approach from the above.
Get the test suite running (use django-discover-runner, tox):
[tox] envlist - py27-django14, py33-django15 py27-django14
Evaluate dependencies
syntax changes
- print vs print()
- django.utils.six
Fix unicode handling:
django.utils.unicode
See Jeff Triplett’s port of django-sitetree
Documentation¶
- django.me/py3
Moving Forward¶
- Django used to be the holdup for moving Python 3 usage forward
- Q&A is at room 201 upstairs