Make device_factory decorator to ease making and connecting ophyd-async Devices

[coretl]

#415 (comment) summarizes a discussion on Device connection.
bluesky/ophyd-async#265 will implement the ophyd-async supporting features of idempotent connect. The strategy we would like for dodal is:

• Each beamline module decorates its device factories with a device_factory
• This factory makes, names, caches and optionally connects a device
• In script use can pass connect=True to the device to connect in the foreground, requires a RunEngine to have been made
• In blueapi use can find all the eager devices and connect them at startup
• Can also connect them in a plan with the ensure_connected plan stub

This ticket is for:

New ADR

Describing how Devices should be connected in dodal, from scripts and under blueapi

dodal.beamlines.beamline_utils

D = TypeVar(bound=Device)
class DeviceFactory(Protocol, Generic[D]):
    def __call__(self, connect: bool = False, timeout: float = DEFAULT_TIMEOUT) -> D:
        ...

_factory_made_devices: Dict[DeviceFactory, Device] = {}
_device_is_lazy: Dict[DeviceFactory, bool] = {}

def device_factory(lazy=False, set_name=True):
    def wrapper(f) -> DeviceFactory[D]:
        def factory(connect=False, timeout: float = DEFAULT_TIMEOUT):
            device = _factory_made_devices.get(f)
            if not device:
                device = f()
                if set_name:
                    device.set_name(f.__name__)
                _factory_made_devices[f] = device
            if connect: 
                call_in_bluesky_event_loop(device.connect(timeout=timeout))
            return device
        _device_is_lazy[factory] = lazy
        factory.__name__ = f.__name__
        return factory
    return wrapper

def get_device_factories() -> Dict[DeviceFactory, bool]:
    return _device_is_lazy.copy()

Need to add type hints to this so it knows the type of device it is making from the function it is decorating and check with @callumforrester that get_device_factories is what blueapi actually needs

Acceptance Criteria

• ADR written so we know why this was done
• device_factory available to use in beamline modules
• i22.py updated to use it

[stan-dot]

so the idea is that all device()... line in i22.py or other beamline gets this decorator, right?

[coretl]

so the idea is that all device()... line in i22.py or other beamline gets this decorator, right?

yes