Change ExEngine motor's API

[jacopoabramo]

I'm currently reviewing a bit the API for the motors and I believe they can be better expressed to be more generic than they currently are.

At the time I believe that they were a starting point to address an initial design; for the application I'm working on I may propose a change that looks something along these lines (affected module is exengine.device_types):

"""
Base classes for device_implementations that can be used by the execution engine
"""

from abc import abstractmethod
import numpy as np
from exengine.kernel.device import Device
from typing import TypedDict, Generic, TypeVar, Sequence

T = TypeVar('T')
X = TypeVar('X')

class Position(TypedDict, Generic[T]):
    """Typed dictionary for describing position values of a positioner.
    
    Parameters
    ----------
    axis : X
        The axis or axes that the value corresponds to.
    """
    
    axis: str
    value: T

class Positioner(Device):
    """ A positioner that can move along a single axis (e.g. a z drive used as a focus stage) """

    @abstractmethod
    def set_position(self, position: Position[float]) -> None:
        """Set the position of the device."""
        ...

    @abstractmethod
    def get_position(self, axis: str) -> Position[float]:
        """Return the position of the device on the specific axis."""
        ...


class TriggerablePositioner(Positioner):
    """
    A special type of positioner that can accept a sequence of positions to move to when provided external TTL triggers
    """
    @abstractmethod
    def set_sequence(self, positions: Sequence[Position[np.ndarray]]) -> None:
        ...

    @abstractmethod
    def get_sequence_length(self) -> int:
        ...

    @abstractmethod
    def stop_sequence(self) -> None:
        ...

I understand that this might be somewhat disruptive of the current situation, but I remember that the initial design was closely related to Micro-Manager APIs. This would give a much needed higher level of flexibility to whoever wants to implement it's own device interface.

EDIT: link typo

[jacopoabramo]

I still think that the typing for triggerable sequences can be done even better, but this is a first draft that came to me on a whim while working on my application.