abcreg 0.1.2

Checked inheritance for Abstract Base Classes

ABCReg

ABCReg adds AnnotatedABC and AnnotatedABCMeta, which provide additional interface checking at registration time to ensure that registered virtual and ordinary subclasses are valid.

Use ABCReg if you are designing a plugin API or any other interface that might be implemented by an end user.

Defining the Interface

Use AnnotatedABC just like an ordinary ABC. Make sure to mark your API methods as abstract and provide type hints:

from abc import abstractmethod
from abcreg import AnnotatedABC

class Queryable(AnnotatedABC):
    @abstractmethod
    def query(self, **kwargs) -> str: ...

We recommend you use virtual inheritance:

@Queryable.register
class VirtualQueryProvider:
    def query(self, **kwargs) -> str:
        return "query result"

assert issubclass(VirtualQueryProvider, Queryable)
assert isinstance(VirtualQueryProvider(), Queryable)

But, regular inheritance will also work:

class QueryProvider(Queryable):
    def query(self, **kwargs) -> str:
        return "query result"

assert issubclass(QueryProvider, Queryable)

Requirements and Usage

Requries Python 3.10+. With UV, require with uv add abcreg.

Development

Pre-build checks:

uv sync --all-groups
uv run ruff check --fix
uv run ruff format --preview
uv run mypy abcreg