Enable use as a context decorator (#128)

Co-authored-by: Hirsch Alter <hirsch@lynxight.com>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

docs/changelog.rst

@@ -1,6 +1,10 @@
 Changelog
 =========
 
+v3.5.0 (2022-01-03)
+-------------------
+- Enable use as context decorator
+
 v3.4.2 (2021-12-16)
 -------------------
 - Drop support for python ``3.6``

docs/index.rst

@@ -67,6 +67,14 @@ locks:
     finally:
         lock.release()
 
+
+    @lock
+    def decorated():
+        print("You're a decorated Jedi!")
+
+
+    decorated()
+
 The :meth:`acquire <filelock.BaseFileLock.acquire>` method accepts also a ``timeout`` parameter. If the lock cannot be
 acquired within ``timeout`` seconds, a :class:`Timeout <filelock.Timeout>` exception is raised:
 

src/filelock/_api.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+import contextlib
 import logging
 import os
 import time
@@ -35,7 +36,7 @@ def __exit__(
         self.lock.release()
 
 
-class BaseFileLock(ABC):
+class BaseFileLock(ABC, contextlib.ContextDecorator):
     """Abstract base class for a file lock object."""
 
     def __init__(self, lock_file: str | os.PathLike[Any], timeout: float = -1) -> None:

tests/test_filelock.py

@@ -368,3 +368,17 @@ def test_poll_intervall_deprecated(lock_type: type[BaseFileLock], tmp_path: Path
                 break
         else:  # pragma: no cover
             pytest.fail("No warnings of stacklevel=2 matching.")
+
+
+@pytest.mark.parametrize("lock_type", [FileLock, SoftFileLock])
+def test_context_decorator(lock_type: type[BaseFileLock], tmp_path: Path) -> None:
+    lock_path = tmp_path / "a"
+    lock = lock_type(str(lock_path))
+
+    @lock
+    def decorated_method() -> None:
+        assert lock.is_locked
+
+    assert not lock.is_locked
+    decorated_method()
+    assert not lock.is_locked