[libgpiod][PATCH 03/14] bindings: python: _internal: collapse isinstance checks

[Vincent Fazio <vfazio@gmail.com>]

The two isinstance checks can be combined to a single call that uses a
tuple of types to check against.

When 8c9d5b4 was prototyped, it originally used a single call but it
was falsely micro-optimized to use two separate calls due to the single
call being slower.

The performance overhead was likely due to the tuple of types being
created on each iteration of the loop. Using a module variable with the
proper types avoids this overhead.

  $ python3 -m timeit -s "x = 42; T = (int, str)" "isinstance(x, T)"
  20000000 loops, best of 5: 13.9 nsec per loop
  $ python3 -m timeit -s "x = 42" "isinstance(x, int) or isinstance(x, str)"
  20000000 loops, best of 5: 14.6 nsec per loop
  $ python3 -m timeit -s "x = 42" "isinstance(x, (int, str))"
  10000000 loops, best of 5: 30 nsec per loop

Fixes: 8c9d5b4 ("bindings: python: make config iteration consistent")
Signed-off-by: Vincent Fazio <vfazio@gmail.com>
---
 bindings/python/gpiod/_internal.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/bindings/python/gpiod/_internal.py b/bindings/python/gpiod/_internal.py
index a4c997d..f0c7450 100644
--- a/bindings/python/gpiod/_internal.py
+++ b/bindings/python/gpiod/_internal.py
@@ -14,6 +14,8 @@ if TYPE_CHECKING:
 
 __all__ = ["config_iter", "poll_fd"]
 
+_LINE_ID_TYPES = (int, str)
+
 
 def poll_fd(fd: int, timeout: timedelta | float | None = None) -> bool:
     sec: float | None
@@ -30,7 +32,7 @@ def config_iter(
     config: dict[Iterable[int | str] | int | str, LineSettings | None],
 ) -> Generator[tuple[int | str, LineSettings | None]]:
     for key, settings in config.items():
-        if isinstance(key, int) or isinstance(key, str):
+        if isinstance(key, _LINE_ID_TYPES):
             yield key, settings
         else:
             for subkey in key:
-- 
2.43.0