Allow setting final instance attributes in __new__
Open
Nobody has claimed this yet.
feature
priority-1-normal
topic-final
- Dominant language
- Python
- Stars
- 20.6k
- Forks
- 3.3k
- PR merge metrics
- PR metrics pending
Description
These patterns should be allowed:
class C:
def __new__(cls, x: int) -> C:
self = object.__new__(cls)
self.x: Final = x
return self
and
class C:
x: Final[int]
def __new__(cls) -> C:
self = object.__new__(cls)
self.x: Final = 1
return self
Currently this is blocked by https://github.com/python/mypy/issues/1021
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
The issue provides no file or test path. Start by tracing mypy's handling of Final instance assignments and new; use the two examples as acceptance cases and confirm that both are accepted without weakening other Final checks.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- python
- Domain
- devtools
- Issue type
- Feature
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100