| Status | Accepted |
|---|---|
| RFC # | 003 |
| Submitted | 2020-11-20 |
| Tribe votes | 👍 (59) |
Declare Python 3.6 as the minimum Python version supported for Conan 2.0 launch. Declare a Python version support policy for 12 months after the minimum supported version has officially become End Of Life (EOL).
Python ecosystem is moving forward, Python 3.5 has reached EOL, and some core Conan dependencies will stop to support it, like requests >2.25.
Python 3.6 has also some valuable features that will help to improve the codebase and write more maintainable source:
- Formatted string literals a.k.a. f-strings.
- Type hints for classes and instance variables.
There is also a support problem when Python officially declares versions EOL, because dependencies stop supporting those versions and can break the Conan application. Conan can pin and restrict the usage of those dependencies newer versions, but that also has security implications, so it is not something that should be extended too much over time.
Python 3.6 will be the minimal supported version. Conan 2.0 is expected to be released on 2021, by that date Python 3.6 will be the oldest release alive (EOL on December 2021) and Python 3.10 will be already released (October 2021).
About Linux distros: starting on Debian 10 Buster (July 2019), the Python 3 version installed is Python 3.7. Ubuntu 18.04 (April 2018) already included Python 3.6.
Conan will drop support for Python versions 12 months after their official EOL date, that is, it will continue testing and supporting one year beyond that date. When one version support becomes deprecated, the next Python version will be used as the minimum tested and supported one.
Newer Python versions provide several enhancements on type annotation that could help to write and maintain code and some nice language features, but those are not needed and can block Conan 2.0 from being deployed on some wide-spread systems.
As soon as we include some f-string in the sources, the test suite will start to fail for any Python version older than 3.6.
Not known yet.
Not applicable.