from abc import ABC, abstractmethod
import os
from pathlib import Path
from types import TracebackType
from typing import Optional, Type, TypeVar, Union
from pydantic import BaseModel, PrivateAttr
AnyPath = Union[str, bytes, "os.PathLike[str]", "os.PathLike[bytes]"]
OC = TypeVar("OC", bound="OpenClosable")
[docs]class OpenClosable(ABC, BaseModel):
"""
An abstract base class for creating reentrant_ context managers. A
concrete subclass must define ``open()`` and ``close()`` methods;
`OpenClosable` will then define ``__enter__`` and ``__exit__`` methods that
keep track of the depth of nested ``with`` statements, calling ``open()``
and ``close()`` only when entering & exiting the outermost ``with``.
.. _reentrant: https://docs.python.org/3/library/contextlib.html
#reentrant-cms
"""
_context_depth: int = PrivateAttr(0)
[docs] @abstractmethod
def open(self) -> None:
...
[docs] @abstractmethod
def close(self) -> None:
...
def __enter__(self: OC) -> OC:
if self._context_depth == 0:
self.open()
self._context_depth += 1
return self
def __exit__(
self,
_exc_type: Optional[Type[BaseException]],
_exc_val: Optional[BaseException],
_exc_tb: Optional[TracebackType],
) -> None:
self._context_depth -= 1
if self._context_depth == 0:
self.close()
[docs]def resolve_path(path: AnyPath, basepath: Optional[AnyPath] = None) -> Path:
"""
Convert a path to a `pathlib.Path` instance and resolve it using the same
rules for as paths in ``outgoing`` configuration files: expand tildes by
calling `Path.expanduser()`, prepend the parent directory of ``basepath``
(usually the value of ``configpath``) to the path if given, and then
resolve the resulting path to make it absolute.
:param path path: the path to resolve
:param path basepath: an optional path to resolve ``path`` relative to
:rtype: pathlib.Path
"""
p = Path(os.fsdecode(path)).expanduser()
if basepath is not None:
p = Path(os.fsdecode(basepath)).parent / p
return p.resolve()