refactor: Replace ad-hoc dispatch with custom @singledispatch
#3410
+338
−105
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This is more generally useful and a LOT easier to read from the outside
dangotbanned
commented
Jan 22, 2026
Comment on lines
+27
to
+29
| # Default implementation serves as a fallback for subclasses of `upper_bound` | ||
| @just_dispatch(upper_bound=DType) | ||
| def dtype_repr_code(dtype: DType) -> str: |
Member
Author
There was a problem hiding this comment.
All of these comments are an attempt at a literate style 🙂
Initially I wanted to have some examples in the docstrings (in _dispatch.py), but:
- Anything non-trivial requires a very large docstring
- I couldn't think of anything simple that captures the strengths of the concept
dangotbanned
commented
Jan 22, 2026
Comment on lines
+57
to
+63
| def register( # noqa: D417 | ||
| self, tp: type[Any], *tps: type[Any] | ||
| ) -> Callable[[Passthrough], Passthrough]: | ||
| """Register types to dispatch via the decorated function. | ||
|
|
||
| Arguments: | ||
| *tps: One or more **concrete** types. |
Member
Author
There was a problem hiding this comment.
I've left out validating the types for now.
3.9:@functools.singledispatchsupportstype[Any]3.10: Same support, but that's the version which introducestypes.UnionType3.11:@functools.singledispatchsupportstyping.Union | types.UnionType | type[Any]
Since #3204 is not resolved, I'd rather leave this runtime check until then
…s/supertyping-dispatch
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Description
Adds a slimmed-down version of
@functools.singledispatch, with the initial use replacing_supertyping._same_supertypein #3396.I can see a few other places (particularly
DType-related) that could later benefit.So, I went ahead and added more tests + docs than I would normally do for an internal tool.
Why not
@functools.singledispatch?Most of the stdlib code is dedicated to two features I don't want to use.
mro-based dispatch
That allows you to register
ABCs (likeMapping,Iterable, etc) or any regular class and have it's subclasses match.Definitely pretty clever stuff, but I'd prefer to have a simpler version that needs every class to be added explicitly
Registration via annotation
Forward references are resolved eagerly1 and only classes and unions of classes are supported.
IMO, that's just a complicated way of accepting
*types: type[Any]in the decorator - so I did that instead 😅Related issues
get_supertype#3396Footnotes
ibishas@lazy_singledispatchthat appears to solve this issue ↩