pyapp-org/pyapp

"""
Base Loader
~~~~~~~~~~~

ABC for loader implementations.

"""
import abc
from typing import Any, Iterable, Sequence, Tuple, Union

from yarl import URL


class Loader(abc.ABC, Iterable[Tuple[str, Any]]):
    """
    ABC class to define the loader interface.
    """

    scheme: Union[str, Sequence[str]]
    """
    Scheme that this loader provides handling of.
    """

    def __enter__(self) -> "Loader":
        return self

    def __exit__(self, exc_type, exc_val, exc_tb):
        self.close()

    @classmethod
    @abc.abstractmethod
    def from_url(cls, url: URL) -> "Loader":
        """
        Create an instance of a `Loader` using the results of the parsed file URL.
        """

    def close(self):
        """
        Called by framework when this loader is no longer required.

        This allows any open handles to be closed or caches to be cleared.
        """