Determine what projects are blocking you from porting to Python 3
This script takes in a set of dependencies and then figures out which of them are holding you up from porting to Python 3.
You can specify your dependencies in multiple ways:
caniusepython3 -r requirements.txt test-requirement.txt caniusepython3 -m PKG-INFO caniusepython3 -p numpy scipy ipython # If your project's setup.py uses setuptools # (note that setup_requires can't be checked) ... python setup.py caniusepython3
The output of the script will tell you how many (implicit) dependencies you need to transition to Python 3 in order to allow you to make the same transition. It will also list what projects have no dependencies blocking their transition so you can ask them to start a port to Python 3.
If you prefer a web interface you can use https://caniusepython3.com by Jannis Leidel.
Integrating With Your Tests
If you want to check for Python 3 availability as part of your tests, you can use caniusepython3.check():
def check(requirements_paths=, metadata=, projects=): """Return True if all of the specified dependencies have been ported to Python 3. The requirements_paths argument takes a sequence of file paths to requirements files. The 'metadata' argument takes a sequence of strings representing metadata. The 'projects' argument takes a sequence of project names. Any project that is not listed on PyPI will be considered ported. """
You can then integrate it into your tests like so:
import unittest import caniusepython3 class DependenciesOnPython3(unittest.TestCase): def test_dependencies(self): # Will begin to fail when dependencies are no longer blocking you # from using Python 3. self.assertFalse(caniusepython3.check(projects=['ipython']))
For the change log, how to tell if a project has been ported, as well as help on how to port a project, please see the project website.
Extending pylint --py3k
In Pylint 1.4, a --py3k option was added to the linting tool to turn on checks for Python 2/3 incompatibilities (all other checks are turned off). While great, those checks are a little conservative in order to always be accurate. To fill out those checks with stricter – albeit potentially inaccurate – checkers, caniusepython3.pylint_checker exists. On top of everything pylint --py3k already checks for, it adds checks for:
- Uses of open() (in Python3, open() is actually io.open())
- String literals that do not have a b/u prefix or from __future__ import unicode_literals
If you wish to use the checker with Pylint, you can add it to your Pylint configuration file, e.g.:
Secret, bonus feature
If you would like to use a different name for the script and setuptools command then set the environment variable CIU_ALT_NAME to what you would like the alternative name to be. Reddit suggests icanhazpython3.
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