Can I Use Python 3?

You can read the documentation on how to use caniusepython3 from its PyPI page. A web interface is also available.

How do you tell if a project has been ported to Python 3?

On PyPI each project can specify various trove classifiers (typically in a project's setup.py through a classifier argument to setup()). There are various classifiers related to what version of Python a project can run on. E.g.:

Programming Language :: Python :: 3
Programming Language :: Python :: 3.0
Programming Language :: Python :: 3.1
Programming Language :: Python :: 3.2
Programming Language :: Python :: 3.3
Programming Language :: Python :: 3.4

As long as a trove classifier for some version of Python 3 is specified then the project is considered to support Python 3 (project owners: it is preferred you at least specify Programming Language :: Python :: 3 as that is how you end up listed on the Python 3 Packages list on PyPI; you can represent Python 2 support with Programming Language :: Python).

The other way is through a manual override in caniusepython3 itself. This list of projects exists because:

• They are now part of Python's standard library in some release of Python 3
• Their Python 3 port is under a different name
• They are missing a Python 3 trove classifier but have actually been ported

If any of these various requirements are met, then a project is considered to support Python 3 and thus will be added to the manual overrides list. You can see the list of overrides when you run the script with verbose output turned on.

How can I get a project ported to Python 3?

Typically projects which have not switched to Python 3 yet are waiting for:

• A dependency to be ported to Python 3
• Someone to volunteer to put in the time and effort to do the port

Since caniusepython3 will tell you what dependencies are blocking a project that you depend on from being ported, you can try to port a project farther down your dependency graph to help a more direct dependency make the transition.

Which brings up the second point: volunteering to do a port. Most projects happily accept help, they just have not done the port yet because they have not had the time. Some projects are simply waiting for people to ask for it, so even speaking up politely and requesting a port can get the process started.

If you are looking for help to port a project, you can always search online for various sources of help. If you want a specific starting point there are HOWTOs in the Python documentation on porting pure Python modules and extension modules.

Change Log

2.1.0

• Verbose output will print what manual overrides are used and why (when available)
• Fix logging to only be configured when running as a script as well as fix a format bug
• Usual override updates

2.0.3

• Fixed setup.py caniusepython3 to work with extras_require properly
• Fix various errors triggered from the moving of the just_name() function to a new module in 2.0.0 (patch by Vaibhav Sagar w/ input from Jannis Leidel)
• Usual overrides tweaks (thanks to CyrilRoelandteNovance for contributing)

2.0.2

• Fix lack of unicode usage in a test
• Make Python 2.6 happy again due to its distate of empty XML-RPC results

2.0.1

• Fix syntax error

2.0.0

• Tweak overrides
• -r, -m, and -p now take 1+ arguments instead of a single comma-separated list
• Unrecognized projects are considered ported to prevent the lack of info on the unrecognized project perpetually suggesting that it's never been ported
• Introduced icanusepython3.check()

1.2.1

• Fix -v to actually do something again
• Tweaked overrides

1.2.0

• -r accepts a comma-separated list of file paths

1.1.0

• Setuptools command support
• Various fixes

1.0

Initial release.