Class KeepOpenFile

src/click/utils.py:207–243

Proxy a file object but keep it open across a ``with`` block. Wraps a borrowed file (such as ``sys.stdin`` or ``sys.stdout``) so that leaving a ``with`` block does not close it, as used by :func:`open_file` for the ``-`` filename. The caller stays responsible for the file: an explic

class KeepOpenFile:
    """Proxy a file object but keep it open across a ``with`` block.

    Wraps a borrowed file (such as ``sys.stdin`` or ``sys.stdout``) so that
    leaving a ``with`` block does not close it, as used by :func:`open_file`
    for the ``-`` filename. The caller stays responsible for the file: an
    explicit :meth:`close` still passes through to the wrapped object.

    Dunder methods are proxied explicitly: implicit special-method lookups
    bypass :meth:`__getattr__`, because Python resolves them on the type rather
    than the instance.
    """

    _file: t.IO[t.Any]

    def __init__(self, file: t.IO[t.Any]) -> None:
        self._file = file

    def __getattr__(self, name: str) -> t.Any:
        return getattr(self._file, name)

    def __enter__(self) -> KeepOpenFile:
        return self

    def __exit__(
        self,
        exc_type: type[BaseException] | None,
        exc_value: BaseException | None,
        tb: TracebackType | None,
    ) -> None:
        pass

    def __repr__(self) -> str:
        return repr(self._file)

    def __iter__(self) -> cabc.Iterator[t.AnyStr]:
        return iter(self._file)


def echo(