pydase/docs/user-guide/Validating-Property-Setters.md

Using validate_set to Validate Property Setters

The validate_set decorator ensures that a property setter reads back the set value using the property getter and checks it against the desired value. This decorator can be used to validate that a parameter has been correctly set on a device within a specified precision and timeout.

The decorator takes two keyword arguments: timeout and precision. The timeout argument specifies the maximum time (in seconds) to wait for the value to be within the precision boundary. If the value is not within the precision boundary after this time, an exception is raised. The precision argument defines the acceptable deviation from the desired value. If precision is None, the value must be exact. For example, if precision is set to 1e-5, the value read from the device must be within ±0.00001 of the desired value.

Here’s how to use the validate_set decorator in a DataService class:

import pydase
from pydase.observer_pattern.observable.decorators import validate_set


class Service(pydase.DataService):
    def __init__(self) -> None:
        super().__init__()
        self._device = RemoteDevice()  # dummy class

    @property
    def value(self) -> float:
        # Implement how to get the value from the remote device...
        return self._device.value

    @value.setter
    @validate_set(timeout=1.0, precision=1e-5)
    def value(self, value: float) -> None:
        # Implement how to set the value on the remote device...
        self._device.value = value


if __name__ == "__main__":
    pydase.Server(service=Service()).run()