adds validate_set decorator

src/pydase/observer_pattern/observable/decorators.py

@@ -0,0 +1,101 @@
+import time
+from collections.abc import Callable
+from typing import TYPE_CHECKING, Any, ParamSpec, TypeVar
+
+if TYPE_CHECKING:
+    from pydase.observer_pattern.observable.observable import Observable
+
+P = ParamSpec("P")
+R = TypeVar("R")
+
+
+def validate_set(
+    *, timeout: float = 0.1, precision: float | None = None
+) -> Callable[[Callable[P, R]], Callable[P, R]]:
+    """
+    Decorator marking a property setter to read back the set value using the property
+    getter and check against the desired value.
+
+    Args:
+        timeout (float):
+            The maximum time (in seconds) to wait for the value to be within the
+            precision boundary.
+        precision (float | None):
+            The acceptable deviation from the desired value. If None, the value must be
+            exact.
+    """
+
+    def validate_set_decorator(func: Callable[P, R]) -> Callable[P, R]:
+        def wrapper(*args: P.args, **kwargs: P.kwargs) -> R:
+            return func(*args, **kwargs)
+
+        wrapper._validate_kwargs = {
+            "timeout": timeout,
+            "precision": precision,
+        }
+
+        return wrapper
+
+    return validate_set_decorator
+
+
+def has_validate_set_decorator(prop: property) -> bool:
+    """
+    Checks if a property setter has been decorated with the `validate_set` decorator.
+
+    Args:
+        prop (property):
+            The property to check.
+
+    Returns:
+        bool:
+            True if the property setter has the `validate_set` decorator, False
+            otherwise.
+    """
+
+    property_setter = prop.fset
+    return hasattr(property_setter, "_validate_kwargs")
+
+
+def _validate_value_was_correctly_set(
+    *,
+    obj: "Observable",
+    name: str,
+    value: Any,
+) -> None:
+    """
+    Validates if the property `name` of `obj` attains the desired `value` within the
+    specified `precision` and time `timeout`.
+
+    Args:
+        obj (Observable):
+            The instance of the class containing the property.
+        name (str):
+            The name of the property to validate.
+        value (Any):
+            The desired value to check against.
+
+    Raises:
+        ValueError:
+            If the property value does not match the desired value within the specified
+            precision and timeout.
+    """
+
+    prop: property = getattr(type(obj), name)
+
+    timeout = prop.fset._validate_kwargs["timeout"]  # type: ignore
+    precision = prop.fset._validate_kwargs["precision"]  # type: ignore
+    if precision is None:
+        precision = 0.0
+
+    start_time = time.time()
+    while time.time() - start_time < timeout:
+        current_value = obj.__getattribute__(name)
+        # This check is faster than rounding and comparing to 0
+        if abs(current_value - value) <= precision:
+            return
+        time.sleep(0.01)
+    raise ValueError(
+        f"Failed to set value to {value} within {timeout} seconds. Current value: "
+        f"{current_value}."
+    )