do not reference _loop

Author: ddkohler

yaqd_horiba/_horiba_mono.py

@@ -5,6 +5,8 @@
 
 from yaqd_core import HasTurret, IsHomeable, HasLimits, HasPosition, IsDaemon
 
+from ._taskset import TaskSet
+
 
 __all__ = ["HoribaMono"]
 
@@ -58,6 +60,7 @@ def __init__(self, name, config, config_filepath):
         self.serial = self._dev.serial_number
         self._gratings = config["gratings"]
         self._units = "nm"
+        self.tasks = TaskSet()
 
         if self._state["turret"] is None:
             self._state["turret"] = list(self._gratings.keys())[0]
@@ -87,7 +90,7 @@ async def _reset_position(self):
     def home(self):
         # Send "Initialize command, which homes the motor"
         self._dev.ctrl_transfer(0x40, 0xB3, wValue=0, wIndex=0)
-        self._loop.create_task(self._reset_position())
+        self.tasks.from_coro(self._reset_position())
 
     def set_turret(self, identifier):
         if identifier not in self._gratings:
@@ -96,7 +99,7 @@ def set_turret(self, identifier):
         self.logger.debug(self._state["turret"], identifier)
         if identifier != self._state["turret"]:
             self._state["turret"] = identifier
-            self._loop.create_task(self._reset_position())
+            self.tasks.from_coro(self._reset_position())
 
     def get_turret(self):
         return self._state["turret"]

yaqd_horiba/_taskset.py

@@ -0,0 +1,18 @@
+"""helper for keeping tasks from premature garbage collection
+"""
+
+
+import asyncio
+
+
+class TaskSet(set):
+    """container class for tasks to keep strong references"""
+    def add(self, task:asyncio.Task):
+        super().add(task)
+        task.add_done_callback(self.discard)
+
+    def from_coro(self, coro):
+        """create task and add to running loop"""
+        task = asyncio.get_running_loop().create_task(coro)
+        self.add(task)
+