accel.py

from typing import Any, Callable, Final, Generic, TypeVar

T = TypeVar("T")


class StructureSpec(Generic[T]):
    required_attrs: list[tuple[str, Callable]]
    optional_attrs: list[tuple[str, Callable]]
    cls: type[T]

    def __init__(
        self,
        req_attrs: list[tuple[str, Callable]],
        optional_attrs: list[tuple[str, Callable]],
        cls: type[T],
    ) -> None:
        self.required_attrs = req_attrs
        self.optional_attrs = optional_attrs
        self.cls = cls


def structure_attrs_fromdict(val: dict[str, Any], spec: StructureSpec[T]) -> T:
    kwargs = {an: ac(val[an]) for an, ac in spec.required_attrs}
    for an, ac in spec.optional_attrs:
        if an in val:
            kwargs[an] = ac(val[an])

    return spec.cls(**kwargs)