feat!: Rename private class _Attempt to backoff.Attempt and make it part of the public API

.github/workflows/ci.yaml

@@ -81,10 +81,10 @@ jobs:
         with:
           persist-credentials: false
       - uses: astral-sh/setup-uv@c771a70e6277c0a99b617c7a806ffedaca235ff9 # v9.0.0
+        with:
+          python-version: ${{ matrix.python-version }}
       - name: Type checks
-        env:
-          TOXENV: typing-${{ matrix.python-version }}
-        run: uvx --with tox-uv tox
+        run: uvx --with tox-uv tox -e typing
       - name: Run tests
         env:
           TOXENV: ${{ matrix.python-version }}

backoff/__init__.py

@@ -12,11 +12,13 @@
 https://github.com/python-backoff/backoff
 """
 
+from backoff._common import Attempt
 from backoff._decorator import aretry_context, on_exception, on_predicate, retry_context
 from backoff._jitter import full_jitter, random_jitter
 from backoff._wait_gen import constant, decay, expo, fibo, runtime
 
 __all__ = [
+    "Attempt",
     "aretry_context",
     "constant",
     "decay",

backoff/_async.py

@@ -6,7 +6,7 @@
 from collections.abc import Callable
 from typing import TYPE_CHECKING, Any, TypeVar
 
-from backoff._common import _Attempt, _RetryState
+from backoff._common import Attempt, _RetryState
 
 if TYPE_CHECKING:
     import sys
@@ -252,7 +252,7 @@ async def aretry_context(
     on_giveup: Iterable[_ContextHandler],
     raise_on_giveup: bool,
     wait_gen_kwargs: dict[str, Any],
-) -> AsyncGenerator[_Attempt, None]:
+) -> AsyncGenerator[Attempt, None]:
     giveup = _ensure_coroutine(giveup)
 
     state = _RetryState(
@@ -263,7 +263,7 @@ async def aretry_context(
     )
     while True:
         state.start_attempt()
-        attempt = _Attempt(exception)
+        attempt = Attempt(exception)
         await _dispatch_handlers(
             handlers=on_try,
             tries=state.tries,

backoff/_common.py

@@ -4,7 +4,8 @@
 import logging
 import time
 import traceback
-from typing import TYPE_CHECKING, Any, TypeVar
+from dataclasses import dataclass, field
+from typing import TYPE_CHECKING, Any, TypeAlias, TypeVar
 
 if TYPE_CHECKING:
     import sys
@@ -26,6 +27,8 @@
     else:
         from typing_extensions import Self
 
+    ExceptionTypes: TypeAlias = type[Exception] | tuple[type[Exception], ...]
+
 
 # Use module-specific logger with a default null handler.
 _logger = logging.getLogger("backoff")
@@ -122,7 +125,8 @@ def next_wait(self, send_value: Any, jitter: _Jitterer | None) -> float:
         return _next_wait(self.wait, send_value, jitter, self.elapsed, self.max_time)
 
 
-class _Attempt:
+@dataclass(slots=True)
+class Attempt:
     """A single attempt yielded by `retry_context`/`aretry_context`.
 
     Used as `with attempt: ...`. Exceptions matching `exception_types` are
@@ -131,16 +135,10 @@ class _Attempt:
     exception at all, is left for the `with` block's normal exit behavior.
     """
 
-    __slots__ = (
-        "exception",
-        "exception_types",
-    )
+    exception_types: ExceptionTypes
+    exception: BaseException | None = field(init=False)
 
-    def __init__(
-        self,
-        exception_types: type[Exception] | tuple[type[Exception], ...],
-    ) -> None:
-        self.exception_types = exception_types
+    def __post_init__(self) -> None:
         self.exception: BaseException | None = None
 
     def __enter__(self) -> Self:
@@ -153,7 +151,6 @@ def __exit__(
         tb: object,
     ) -> bool:
         if exc_type is None:
-            # self.outcome = _Success()
             return False
 
         if not issubclass(exc_type, self.exception_types):

backoff/_decorator.py

@@ -20,7 +20,7 @@
 if TYPE_CHECKING:
     from collections.abc import AsyncGenerator, Callable, Generator, Iterable
 
-    from backoff._common import _Attempt
+    from backoff._common import Attempt
     from backoff._typing import (
         _AnyLoggerOrName,
         _CallableT,
@@ -301,7 +301,7 @@ def retry_context(
     backoff_log_level: int = logging.INFO,
     giveup_log_level: int = logging.ERROR,
     **wait_gen_kwargs: Any,
-) -> Generator[_Attempt, None, None]:
+) -> Generator[Attempt, None, None]:
     """Returns a generator of retry attempts, for direct use with a `for` loop.
 
     Unlike `on_exception`, this doesn't wrap a whole function; it lets a
@@ -400,7 +400,7 @@ def aretry_context(
     backoff_log_level: int = logging.INFO,
     giveup_log_level: int = logging.ERROR,
     **wait_gen_kwargs: Any,
-) -> AsyncGenerator[_Attempt, None]:
+) -> AsyncGenerator[Attempt, None]:
     """Async counterpart to `retry_context`, for use with `async for`.
 
         async for attempt in backoff.aretry_context(ValueError, backoff.expo):

backoff/_sync.py

@@ -4,7 +4,7 @@
 import time
 from typing import TYPE_CHECKING, Any, TypeVar
 
-from backoff._common import _Attempt, _dispatch_handlers, _RetryState
+from backoff._common import Attempt, _dispatch_handlers, _RetryState
 
 if TYPE_CHECKING:
     import sys
@@ -188,7 +188,7 @@ def retry_context(
     on_giveup: Iterable[_ContextHandler],
     raise_on_giveup: bool,
     wait_gen_kwargs: dict[str, Any],
-) -> Generator[_Attempt, None, None]:
+) -> Generator[Attempt, None, None]:
     state = _RetryState(
         wait_gen,
         wait_gen_kwargs,
@@ -197,7 +197,7 @@ def retry_context(
     )
     while True:
         state.start_attempt()
-        attempt = _Attempt(exception)
+        attempt = Attempt(exception)
         _dispatch_handlers(handlers=on_try, tries=state.tries, elapsed=state.elapsed)
         yield attempt
         elapsed = state.record_elapsed()

backoff/types.py

@@ -1,5 +1,6 @@
-from ._typing import Details
+from ._typing import ContextDetails, Details
 
 __all__ = [
+    "ContextDetails",
     "Details",
 ]

docs/api/reference.md

@@ -26,6 +26,12 @@ Complete API documentation for the backoff module.
       show_root_heading: true
       show_source: true
 
+::: backoff.Attempt
+    options:
+      show_root_heading: true
+      show_source: true
+      summary: true
+
 ## Wait Generators
 
 ::: backoff.expo

docs/user-guide/context-manager.md

@@ -17,3 +17,36 @@ for attempt in backoff.retry_context():
         else:
             print(f"Got it (choice={choice})")
 ```
+
+`attempt` is an instance of `backoff.Attempt`, so a helper that
+accepts one (e.g. for logging) can be typed against it directly:
+
+```python
+from backoff import Attempt
+
+
+def log_attempt(attempt: Attempt) -> None:
+    print(f"exception so far: {attempt.exception}")
+
+
+for attempt in backoff.retry_context():
+    with attempt:
+        log_attempt(attempt)
+        # ...
+```
+
+Handlers passed as `on_try`/`on_success`/`on_backoff`/`on_giveup` receive a
+`dict` typed as `backoff.types.ContextDetails`:
+
+```python
+from backoff.types import ContextDetails
+
+
+def log_backoff(details: ContextDetails) -> None:
+    print(f"retrying in {details['wait']}s after {details.get('exception')}")
+
+
+for attempt in backoff.retry_context(on_backoff=log_backoff):
+    with attempt:
+        ...
+```

pyproject.toml

@@ -133,20 +133,13 @@ commands = [
 ]
 
 [tool.tox.env.typing]
-base = [ "tool.tox.env_base.typing" ]
-base_python_file = [ ".python-version" ]
-description = "run type checking on the default Python version"
-
-[tool.tox.env_base.typing]
-factors = [
-  { prefix = "3.", start = 10 },
-]
 description = "run type checking on Python {py_dot_ver}"
 dependency_groups = [ "typing" ]
 labels = [ "check" ]
 commands = [
   [
     "mypy",
+    "--python-version={py_dot_ver}",
     "--show-error-codes",
     { replace = "posargs", default = [
       "backoff",
@@ -155,6 +148,7 @@ commands = [
   ],
   [
     "mypy",
+    "--python-version={py_dot_ver}",
     "--strict",
     "--disallow-any-decorated",
     "--follow-imports=silent",
@@ -163,6 +157,7 @@ commands = [
   [
     "ty",
     "check",
+    "--python-version={py_dot_ver}",
     { replace = "if", condition = "env.GITHUB_ACTIONS == 'true'", then = [ "--output-format=github" ], else = [], extend = true },
     { replace = "posargs", default = [
       "backoff",
@@ -172,6 +167,7 @@ commands = [
   [
     "pyrefly",
     "check",
+    "--python-version={py_dot_ver}",
     { replace = "if", condition = "env.GITHUB_ACTIONS == 'true'", then = [ "--output-format=github" ], else = [], extend = true },
     { replace = "posargs", default = [
       "backoff",
@@ -182,6 +178,7 @@ commands = [
     "pyrefly",
     "coverage",
     "check",
+    "--python-version={py_dot_ver}",
     { replace = "if", condition = "env.GITHUB_ACTIONS == 'true'", then = [ "--output-format=github" ], else = [], extend = true },
     { replace = "posargs", default = [
       "backoff",

tests/test_types.py

@@ -1,3 +1,4 @@
-from backoff.types import Details
+from backoff.types import ContextDetails, Details
 
 assert Details  # type: ignore[truthy-function]
+assert ContextDetails  # type: ignore[truthy-function]