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Add type annotations to the module and the unit tests#6

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andlaus wants to merge 3 commits into
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andlaus:add_type_annotations
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Add type annotations to the module and the unit tests#6
andlaus wants to merge 3 commits into
cantools:masterfrom
andlaus:add_type_annotations

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@andlaus

@andlaus andlaus commented Jun 8, 2026

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For some of these I am not 100% sure if they are correct.

A lot of the code churn of this patch stems from the fact that some classes had to be reordered because python bails out if annotations use classes that are only defined later in the file.

This patch features a few minor functional changes which were neccessiated by type annotations:

  • Support for python2 is no longer declared in setup.py
  • The Parser.grammar() methods always return Grammar objects instead of a Pattern object which gets implicitly converted to Grammar in Parser.parse(). (IMO this makes the whole affair much less confusing and user code only needs to return Grammar(x) instead of x.)
  • The _Token class is converted from namedtuple to a dataclass because named tuples do not play nicely with type annotations and the performance is basically identical.
  • The internal _String class now uses Pattern as its base class. (It already had the same API as Pattern, but not deriving _String from Pattern would necessiate _String to be handled separately anyway.)

@andlaus andlaus requested a review from zariiii9003 June 8, 2026 11:27
@andlaus

andlaus commented Jun 8, 2026

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@ilanbiala: with this, it should be possible to implement full type hinting support for the DBC submodule of cantools...

@andlaus

andlaus commented Jun 8, 2026

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updated python version tested in CI to 3.10 and 3.14. (python 3.8 has been EOL for a while.)

@andlaus andlaus force-pushed the add_type_annotations branch from c3d76d3 to 2ddd392 Compare June 8, 2026 11:38
@andlaus

andlaus commented Jun 8, 2026

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fun fact: github "simplifies" the 3.10 version specifier to 3.1. adding quotes around the versions fixes that...

@eerimoq

eerimoq commented Jun 8, 2026

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It’s because 3.10 is a number, both in yaml and json. It’s a bit silly that GitHub accepts anything but strings :)

@ilanbiala

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@andlaus is it possible to split out the Python version bump changes into a separate PR and merge that first to isolate this work?

@ilanbiala

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Hey @eerimoq! Sorry to bring this up here, but would it be possible for you to give @andlaus, @zariiii9003, myself, and others more access to the cantools repo and for the readthedocs site for Cantools as well (cantools/cantools#746)?

@andlaus

andlaus commented Jun 8, 2026

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@andlaus is it possible to split out the Python version bump changes into a separate PR and merge that first to isolate this work?

yes, but the version bump needs to be done before adding the type hints. be aware that the minimum python version is currently not codified in setup.py: setup.py only specifies the Programming Language :: Python :: {2,3} (informal) classifiers and the yaml for github action mentions python 3.8 and 3.13 a few times, i.e., it is currently tested on python 3.8 and 3.14 (but not 2.x) and there's no formal dependency...

@eerimoq

eerimoq commented Jun 9, 2026

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Hey @eerimoq! Sorry to bring this up here, but would it be possible for you to give @andlaus, @zariiii9003, myself, and others more access to the cantools repo and for the readthedocs site for Cantools as well (cantools/cantools#746)?

what exactly?

@ilanbiala

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@eerimoq the Cantools readthedocs site is stuck on a commit that's 2.5 years old and a few version releases out of date (commit revision is at the bottom of the docs site). It looks like permissions haven't been set up correctly for other people to push to the docs site.

For some of these I am not 100% sure if they are correct.

A lot of the code churn of this patch stems from the fact that some
classes had to be reordered because python bails out if annotations
use classes that are only defined later in the file.

This patch features a few minor functional changes which were
neccessiated by type annotations:

- Support for python2 is no longer declared in `setup.py`
- The `Parser.grammar()` methods are supposed to return `Grammar`
  objects instead of a `Pattern` object which gets implicitly
  converted to `Grammar` in `Parser.parse()`. IMO this makes the whole
  affair much less confusing and user code only needs to return
  `Grammar(x)` instead of `x`. If `grammar()` returns something else,
  the old behavior is fallen back to, but this will lead to `mypy`
  complaints in user code...
- The `_Token` class is converted from `namedtuple` to a dataclass
  because named tuples do not play nicely with type annotations and
  the performance is basically identical.
- The internal `_String` class now uses `Pattern` as its base
  class. (It already had the same API as `Pattern`, but not deriving
  `_String` from Pattern would necessiate `_String` to be handled
  separately anyway.)

Signed-off-by: Andreas Lauser <andreas.lauser@mercedes-benz.com>
Approved-by: Christian Hackenbeck <christian.hackenbeck@mercedes-benz.com>
@andlaus andlaus force-pushed the add_type_annotations branch from a45598c to 79df0af Compare June 9, 2026 13:35
@andlaus

andlaus commented Jun 9, 2026

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ok, I rebased this on top of the latest master version, i.e., no need to fiddle with the python versions anymore...

@zariiii9003

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@andlaus could you update the gha config to run mypy in CI?

@andlaus

andlaus commented Jun 9, 2026

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good idea. I also added a ruff linting step.

andlaus added 2 commits June 9, 2026 17:26
thanks to [at]zariiii9003 for the suggestion!

Signed-off-by: Andreas Lauser <andreas.lauser@mercedes-benz.com>
also fix the complaint about the unused import of the `typing` module.

Signed-off-by: Andreas Lauser <andreas.lauser@mercedes-benz.com>
@andlaus andlaus force-pushed the add_type_annotations branch from 724b63c to 64b4204 Compare June 9, 2026 15:27
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4 participants