From b69af18e94e6a5429db43ceeaf1c1aecef40142e Mon Sep 17 00:00:00 2001
From: ivan-borovets <130386813+ivan-borovets@users.noreply.github.com>
Date: Thu, 4 Sep 2025 04:26:09 +0500
Subject: [PATCH] Add remark about slots usage in ValueObject

---
 src/app/domain/value_objects/base.py | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/src/app/domain/value_objects/base.py b/src/app/domain/value_objects/base.py
index faa3036..27bd16a 100644
--- a/src/app/domain/value_objects/base.py
+++ b/src/app/domain/value_objects/base.py
@@ -9,9 +9,24 @@
 class ValueObject:
     """
     Base class for immutable value objects (VO) in domain.
-    Defined by its attributes, which must themselves be immutable.
+    Defined by its instance attributes, which must themselves be immutable.
     For simple cases where only type distinction is required,
     consider using `typing.NewType` instead of subclassing this class.
+
+    Warning: due to mismatch between typing rules and runtime behavior
+    for `Final[ClassVar[T]]`, using `__slots__` in subclasses is not
+    recommended — such class constants are turned into `member_descriptor`
+    at runtime instead of preserving their declared values.
+
+    Note: I considered using plain `ClassVar[T]` for class constants
+    (as `ClassVar[Final[T]]` currently has no semantic meaning anyway)
+    which would immediately resolve the slots compatibility and `fields()`
+    behavior issues. However, I chose to prioritize correct typing
+    semantics with `Final[ClassVar[T]]` and observe how this inconsistency
+    between typing rules and runtime behavior gets resolved.
+
+    https://github.com/python/cpython/issues/89547
+    https://github.com/python/mypy/issues/19607
     """
 
     def __post_init__(self) -> None: