Reimplement DeviceCollector as auto_init_devices

Functionality is the same, but the public interface is now a function rather than a class.
Also makes sure that Devices that exist on entry, and are redeclared in the context manager are found.

docs/examples/epics_demo.py

@@ -7,7 +7,7 @@
 from bluesky.utils import ProgressBarManager, register_transform
 from ophyd import Component, Device, EpicsSignal, EpicsSignalRO
 
-from ophyd_async.core import DeviceCollector
+from ophyd_async.core import auto_init_devices
 from ophyd_async.epics import demo
 
 # Create a run engine, with plotting, progressbar and transform
@@ -31,7 +31,7 @@ class OldSensor(Device):
 det_old = OldSensor(pv_prefix, name="det_old")
 
 # Create ophyd-async devices
-with DeviceCollector():
+with auto_init_devices():
     det = demo.Sensor(pv_prefix)
     det_group = demo.SensorGroup(pv_prefix)
     samp = demo.SampleStage(pv_prefix)

src/ophyd_async/core/__init__.py

@@ -5,7 +5,7 @@
     StandardDetector,
     TriggerInfo,
 )
-from ._device import Device, DeviceCollector, DeviceConnector, DeviceVector
+from ._device import Device, DeviceConnector, DeviceVector, auto_init_devices
 from ._device_filler import DeviceFiller
 from ._flyer import FlyerController, StandardFlyer
 from ._hdf_dataset import HDFDataset, HDFFile
@@ -87,7 +87,7 @@
     "TriggerInfo",
     "Device",
     "DeviceConnector",
-    "DeviceCollector",
+    "auto_init_devices",
     "DeviceVector",
     "DeviceFiller",
     "StandardFlyer",

src/ophyd_async/core/_device.py

@@ -2,7 +2,7 @@
 
 import asyncio
 import sys
-from collections.abc import Coroutine, Iterator, Mapping, MutableMapping
+from collections.abc import Awaitable, Callable, Iterator, Mapping, MutableMapping
 from functools import cached_property
 from logging import LoggerAdapter, getLogger
 from typing import Any, TypeVar
@@ -254,54 +254,18 @@ def __hash__(self):  # to allow DeviceVector to be used as dict keys and in sets
         return hash(id(self))
 
 
-class DeviceCollector:
-    """Collector of top level Device instances to be used as a context manager
-
-    Parameters
-    ----------
-    set_name:
-        If True, call ``device.set_name(variable_name)`` on all collected
-        Devices
-    child_name_separator:
-        Use this as a separator if we call ``set_name``.
-    connect:
-        If True, call ``device.connect(mock)`` in parallel on all
-        collected Devices
-    mock:
-        If True, connect Signals in simulation mode
-    timeout:
-        How long to wait for connect before logging an exception
-
-    Notes
-    -----
-    Example usage::
-
-        [async] with DeviceCollector():
-            t1x = motor.Motor("BLxxI-MO-TABLE-01:X")
-            t1y = motor.Motor("pva://BLxxI-MO-TABLE-01:Y")
-            # Names and connects devices here
-        assert t1x.comm.velocity.source
-        assert t1x.name == "t1x"
+class DeviceContextManager:
+    """Sync/Async Context Manager that finds all the Devices declared within it.
 
+    Used in `auto_init`
     """
 
-    def __init__(
-        self,
-        set_name=True,
-        child_name_separator: str = "-",
-        connect=True,
-        mock=False,
-        timeout: float = 10.0,
-    ):
-        self._set_name = set_name
-        self._child_name_separator = child_name_separator
-        self._connect = connect
-        self._mock = mock
-        self._timeout = timeout
-        self._names_on_enter: set[str] = set()
-        self._objects_on_exit: dict[str, Any] = {}
-
-    def _caller_locals(self):
+    def __init__(self, process_devices: Callable[[dict[str, Device]], Awaitable[None]]):
+        self._process_devices = process_devices
+        self._locals_on_enter: dict[str, Any] = {}
+        self._locals_on_exit: dict[str, Any] = {}
+
+    def _caller_locals(self) -> dict[str, Any]:
         """Walk up until we find a stack frame that doesn't have us as self"""
         try:
             raise ValueError
@@ -314,34 +278,18 @@ def _caller_locals(self):
                 assert (
                     caller_frame
                 ), "No previous frame to the one with self in it, this shouldn't happen"
-            return caller_frame.f_locals
+            return caller_frame.f_locals.copy()
 
-    def __enter__(self) -> DeviceCollector:
+    def __enter__(self) -> DeviceContextManager:
         # Stash the names that were defined before we were called
-        self._names_on_enter = set(self._caller_locals())
+        self._locals_on_enter = self._caller_locals()
         return self
 
-    async def __aenter__(self) -> DeviceCollector:
+    async def __aenter__(self) -> DeviceContextManager:
         return self.__enter__()
 
-    async def _on_exit(self) -> None:
-        # Name and kick off connect for devices
-        connect_coroutines: dict[str, Coroutine] = {}
-        for name, obj in self._objects_on_exit.items():
-            if name not in self._names_on_enter and isinstance(obj, Device):
-                if self._set_name and not obj.name:
-                    obj.set_name(name, child_name_separator=self._child_name_separator)
-                if self._connect:
-                    connect_coroutines[name] = obj.connect(
-                        self._mock, timeout=self._timeout
-                    )
-
-        # Connect to all the devices
-        if connect_coroutines:
-            await wait_for_connection(**connect_coroutines)
-
     async def __aexit__(self, type, value, traceback):
-        self._objects_on_exit = self._caller_locals()
+        self._locals_on_exit = self._caller_locals()
         await self._on_exit()
 
     def __exit__(self, type_, value, traceback):
@@ -350,7 +298,7 @@ def __exit__(self, type_, value, traceback):
                 "Cannot use DeviceConnector inside a plan, instead use "
                 "`yield from ophyd_async.plan_stubs.ensure_connected(device)`"
             )
-        self._objects_on_exit = self._caller_locals()
+        self._locals_on_exit = self._caller_locals()
         try:
             fut = call_in_bluesky_event_loop(self._on_exit())
         except RuntimeError as e:
@@ -360,3 +308,62 @@ def __exit__(self, type_, value, traceback):
                 "user/explanations/event-loop-choice.html for more info."
             ) from e
         return fut
+
+    async def _on_exit(self) -> None:
+        # Find all the devices
+        devices = {
+            name: obj
+            for name, obj in self._locals_on_exit.items()
+            if isinstance(obj, Device) and self._locals_on_enter.get(name) is not obj
+        }
+        # Call the provided process function on them
+        await self._process_devices(devices)
+
+
+def auto_init_devices(
+    set_name=True,
+    child_name_separator: str = "-",
+    connect=True,
+    mock=False,
+    timeout: float = 10.0,
+) -> DeviceContextManager:
+    """Auto initialise top level Device instances to be used as a context manager
+
+    Parameters
+    ----------
+    set_name:
+        If True, call ``device.set_name(variable_name)`` on all Devices
+        created within the context manager that have an empty ``name``
+    child_name_separator:
+        Use this as a separator if we call ``set_name``.
+    connect:
+        If True, call ``device.connect(mock, timeout)`` in parallel on all
+        Devices created within the context manager
+    mock:
+        If True, connect Signals in mock mode
+    timeout:
+        How long to wait for connect before logging an exception
+
+    Notes
+    -----
+    Example usage::
+
+        [async] with auto_init_devices():
+            t1x = motor.Motor("BLxxI-MO-TABLE-01:X")
+            t1y = motor.Motor("pva://BLxxI-MO-TABLE-01:Y")
+            # Names and connects devices here
+        assert t1x.name == "t1x"
+    """
+
+    async def process_devices(devices: dict[str, Device]):
+        if set_name:
+            for name, device in devices.items():
+                if not device.name:
+                    device.set_name(name, child_name_separator=child_name_separator)
+        if connect:
+            coros = {
+                name: device.connect(mock, timeout) for name, device in devices.items()
+            }
+            await wait_for_connection(**coros)
+
+    return DeviceContextManager(process_devices)

system_tests/epics/eiger/test_eiger_system.py

@@ -9,8 +9,8 @@
 from ophyd_async.core import (
     DetectorTrigger,
     Device,
-    DeviceCollector,
     StaticPathProvider,
+    auto_init_devices,
 )
 from ophyd_async.epics.core import epics_signal_rw
 from ophyd_async.epics.eiger import EigerDetector, EigerTriggerInfo
@@ -47,7 +47,7 @@ def RE():
 
 @pytest.fixture
 async def setup_device(RE, ioc_prefixes):
-    async with DeviceCollector():
+    async with auto_init_devices():
         device = SetupDevice(ioc_prefixes[0], ioc_prefixes[1] + "FP:")
     await asyncio.gather(
         device.header_detail.set("all"),
@@ -62,7 +62,7 @@ async def setup_device(RE, ioc_prefixes):
 @pytest.fixture
 async def test_eiger(RE, ioc_prefixes) -> EigerDetector:
     provider = StaticPathProvider(lambda: "test_eiger", Path(SAVE_PATH))
-    async with DeviceCollector():
+    async with auto_init_devices():
         test_eiger = EigerDetector("", provider, ioc_prefixes[0], ioc_prefixes[1])
 
     return test_eiger

tests/core/test_device_collector.py → tests/core/test_auto_init_devices.py

@@ -7,8 +7,8 @@
 from ophyd_async.core import (
     DEFAULT_TIMEOUT,
     Device,
-    DeviceCollector,
     NotConnected,
+    auto_init_devices,
 )
 from ophyd_async.epics import motor
 from ophyd_async.testing import set_mock_value
@@ -33,10 +33,10 @@ async def connect(
     async def set(self, new_position: float): ...
 
 
-async def test_device_collector_handles_top_level_errors(caplog):
+async def test_auto_init_handles_top_level_errors(caplog):
     caplog.set_level(10)
     with pytest.raises(NotConnected) as exc:
-        async with DeviceCollector():
+        async with auto_init_devices():
             _ = FailingDevice("somename")
 
     assert not exc.value.__cause__
@@ -52,9 +52,9 @@ async def test_device_collector_handles_top_level_errors(caplog):
     assert device_log[0].levelname == "ERROR"
 
 
-def test_sync_device_connector_no_run_engine_raises_error():
+def test_sync_auto_init_no_run_engine_raises_error():
     with pytest.raises(NotConnected) as e:
-        with DeviceCollector():
+        with auto_init_devices():
             working_device = WorkingDevice("somename")
     assert e.value._errors == (
         "Could not connect devices. Is the bluesky event loop running? See "
@@ -64,26 +64,36 @@ def test_sync_device_connector_no_run_engine_raises_error():
     assert not working_device.connected
 
 
-def test_sync_device_connector_run_engine_created_connects(RE):
-    with DeviceCollector():
+def test_sync_auto_init_run_engine_created_connects(RE):
+    with auto_init_devices():
         working_device = WorkingDevice("somename")
 
     assert working_device.connected
 
 
+async def test_auto_init_detects_redeclared_devices():
+    original_working_device = working_device = WorkingDevice()
+
+    async with auto_init_devices():
+        working_device = WorkingDevice()
+    assert original_working_device is not working_device
+    assert working_device.connected and working_device.name == "working_device"
+    assert not original_working_device.connected and original_working_device.name == ""
+
+
 def test_connecting_in_plan_raises(RE):
     def bad_plan():
         yield from bps.null()
-        with DeviceCollector():
+        with auto_init_devices():
             working_device = WorkingDevice("somename")  # noqa: F841
 
     with pytest.raises(RuntimeError, match="Cannot use DeviceConnector inside a plan"):
         RE(bad_plan())
 
 
-def test_async_device_connector_run_engine_same_event_loop():
+def test_async_auto_init_run_engine_same_event_loop():
     async def set_up_device():
-        async with DeviceCollector(mock=True):
+        async with auto_init_devices(mock=True):
             mock_motor = motor.Motor("BLxxI-MO-TABLE-01:X")
         set_mock_value(mock_motor.velocity, 1)
         return mock_motor
@@ -126,17 +136,17 @@ def my_plan():
         "loop to set the value, unlike real signals."
     )
 )
-def test_async_device_connector_run_engine_different_event_loop():
+def test_async_auto_init_run_engine_different_event_loop():
     async def set_up_device():
-        async with DeviceCollector(mock=True):
+        async with auto_init_devices(mock=True):
             mock_motor = motor.Motor("BLxxI-MO-TABLE-01:X")
         return mock_motor
 
-    device_connector_loop = asyncio.new_event_loop()
+    auto_init_loop = asyncio.new_event_loop()
     run_engine_loop = asyncio.new_event_loop()
-    assert run_engine_loop is not device_connector_loop
+    assert run_engine_loop is not auto_init_loop
 
-    mock_motor = device_connector_loop.run_until_complete(set_up_device())
+    mock_motor = auto_init_loop.run_until_complete(set_up_device())
 
     RE = RunEngine(loop=run_engine_loop)
 
@@ -147,7 +157,7 @@ def my_plan():
 
     # The set should fail since the run engine is on a different event loop
     assert (
-        device_connector_loop.run_until_complete(mock_motor.user_setpoint.read())[
+        auto_init_loop.run_until_complete(mock_motor.user_setpoint.read())[
             "mock_motor-user_setpoint"
         ]["value"]
         != 3.14

tests/core/test_device.py

@@ -8,11 +8,11 @@
 from ophyd_async.core import (
     DEFAULT_TIMEOUT,
     Device,
-    DeviceCollector,
     DeviceVector,
     NotConnected,
     Reference,
     SignalRW,
+    auto_init_devices,
     soft_signal_rw,
     wait_for_connection,
 )
@@ -126,8 +126,8 @@ async def test_children_of_device_with_different_separator(
         assert parent.dict_with_children[123].name == "parent_dict_with_children_123"
 
 
-async def test_device_with_device_collector():
-    async with DeviceCollector(mock=True):
+async def test_device_with_auto_init():
+    async with auto_init_devices(mock=True):
         parent = DummyDeviceGroup("parent")
 
     assert parent.name == "parent"