(🎁) Allow if expression / conditional base in class def
Open
Nobody has claimed this yet.
feature
priority-2-low
semantic-analyzer
topic-ternary-expression
- Dominant language
- Python
- Stars
- 20.6k
- Forks
- 3.3k
- PR merge metrics
- PR metrics pending
Description
I have some proxy objects and it's difficult to type them, I want to lie to mypy what the bases are
from typing import TYPE_CHECKING
class A: ...
class B: ...
class C(A if TYPE_CHECKING else B): ... # error: Invalid base class [misc]
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
Start by reproducing the issue's conditional-base example with mypy and trace how class bases are analyzed and reported as invalid. Done means the shown TYPE_CHECKING conditional base is accepted without the Invalid base class diagnostic, with regression coverage for the example.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- python
- Domain
- compilers
- Issue type
- Feature
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100