[libgpiod][PATCH 09/22] bindings: python: fix LineRequest union-attr type errors

[Vincent Fazio <vfazio@xxxxxxxxxxx>]

Since `LineRequest._req` can be `None`, it's necessary to inform type
checkers of the state of the object to silence the union-attr errors.

Type checkers may not be able to infer that an object is not `None` from
an earlier call (such as `_check_released`).

Instead of littering the code with "# type: ignore" comments, use casts
to inform type checkers that objects are not `None`.

Using `assert` is another option, however this duplicates the logic in
`_check_released` so is redundant at best and, at worst, is not a safe
replacement as `assert` can be elided in optimized Python environments
and these checks need to be runtime enforced.

Also, convert singular ints or strs to a tuple instead of a list to keep
with the inferred variable type of `lines`.

Signed-off-by: Vincent Fazio <vfazio@xxxxxxxxxxx>
---
 bindings/python/gpiod/line_request.py | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/bindings/python/gpiod/line_request.py b/bindings/python/gpiod/line_request.py
index 77d199ac64e9d3cc68d4a8b38dd0f571a24ab231..6c57f612a4167061945e798e93f069689723b583 100644
--- a/bindings/python/gpiod/line_request.py
+++ b/bindings/python/gpiod/line_request.py
@@ -6,7 +6,7 @@ from __future__ import annotations
 from collections.abc import Iterable
 from datetime import timedelta
 from types import TracebackType
-from typing import Optional, Union
+from typing import Optional, Union, cast
 
 from . import _ext
 from ._internal import poll_fd
@@ -74,6 +74,7 @@ class LineRequest:
         not be used after a call to this method.
         """
         self._check_released()
+        self._req = cast(_ext.Request, self._req)
         self._req.release()
         self._req = None
 
@@ -114,6 +115,7 @@ class LineRequest:
           List of logical line values.
         """
         self._check_released()
+        self._req = cast(_ext.Request, self._req)
 
         lines = lines or self._lines
 
@@ -148,6 +150,7 @@ class LineRequest:
             Dictionary mapping line offsets or names to desired values.
         """
         self._check_released()
+        self._req = cast(_ext.Request, self._req)
 
         mapped = {
             self._name_map[line] if self._check_line_name(line) else line: values[line]
@@ -173,13 +176,14 @@ class LineRequest:
             Any settings for non-requested lines are ignored.
         """
         self._check_released()
+        self._req = cast(_ext.Request, self._req)
 
         line_cfg = _ext.LineConfig()
         line_settings = {}
 
         for lines, settings in config.items():
             if isinstance(lines, int) or isinstance(lines, str):
-                lines = [lines]
+                lines = (lines,)
 
             for line in lines:
                 offset = self._name_map[line] if self._check_line_name(line) else line
@@ -222,6 +226,7 @@ class LineRequest:
           List of read EdgeEvent objects.
         """
         self._check_released()
+        self._req = cast(_ext.Request, self._req)
 
         return self._req.read_edge_events(max_events)
 
@@ -275,4 +280,5 @@ class LineRequest:
         File descriptor associated with this request.
         """
         self._check_released()
+        self._req = cast(_ext.Request, self._req)
         return self._req.fd

-- 
2.34.1