Add typing annotations for functions in can.bus

This adds typing annotations for use via mypy for all functions under
can.bus.

This works towards PEP 561 compatibility.

Author: karlding

can/bus.py

@@ -4,6 +4,8 @@
 Contains the ABC bus implementation and its documentation.
 """
 
+from typing import Any, Dict, Iterable, Iterator, List, Optional, Sequence, Union
+
 from abc import ABCMeta, abstractmethod
 import can
 import logging
@@ -38,7 +40,12 @@ class BusABC(metaclass=ABCMeta):
     RECV_LOGGING_LEVEL = 9
 
     @abstractmethod
-    def __init__(self, channel, can_filters=None, **kwargs):
+    def __init__(
+        self,
+        channel: Any,
+        can_filters: Optional[List[Dict[str, Union[bool, int, str]]]] = None,
+        **kwargs: object
+    ):
         """Construct and open a CAN bus instance of the specified type.
 
         Subclasses should call though this method with all given parameters
@@ -53,13 +60,13 @@ def __init__(self, channel, can_filters=None, **kwargs):
         :param dict kwargs:
             Any backend dependent configurations are passed in this dictionary
         """
-        self._periodic_tasks = []
+        self._periodic_tasks: List[can.broadcastmanager.CyclicSendTaskABC] = []
         self.set_filters(can_filters)
 
-    def __str__(self):
+    def __str__(self) -> str:
         return self.channel_info
 
-    def recv(self, timeout=None):
+    def recv(self, timeout: Optional[float] = None) -> Optional[can.Message]:
         """Block waiting for a message from the Bus.
 
         :type timeout: float or None
@@ -100,7 +107,7 @@ def recv(self, timeout=None):
                 else:
                     return None
 
-    def _recv_internal(self, timeout):
+    def _recv_internal(self, timeout: Optional[float]):
         """
         Read a message from the bus and tell whether it was filtered.
         This methods may be called by :meth:`~can.BusABC.recv`
@@ -144,7 +151,7 @@ def _recv_internal(self, timeout):
         raise NotImplementedError("Trying to read from a write only bus?")
 
     @abstractmethod
-    def send(self, msg, timeout=None):
+    def send(self, msg: can.Message, timeout: Optional[float] = None):
         """Transmit a message to the CAN bus.
 
         Override this method to enable the transmit path.
@@ -164,7 +171,13 @@ def send(self, msg, timeout=None):
         """
         raise NotImplementedError("Trying to write to a readonly bus?")
 
-    def send_periodic(self, msgs, period, duration=None, store_task=True):
+    def send_periodic(
+        self,
+        msgs: Union[Sequence[can.Message], can.Message],
+        period: float,
+        duration: Optional[float] = None,
+        store_task: bool = True,
+    ) -> can.broadcastmanager.CyclicSendTaskABC:
         """Start sending messages at a given period on this bus.
 
         The task will be active until one of the following conditions are met:
@@ -223,14 +236,19 @@ def wrapped_stop_method(remove_task=True):
                     pass
             original_stop_method()
 
-        task.stop = wrapped_stop_method
+        setattr(task, "stop", wrapped_stop_method)
 
         if store_task:
             self._periodic_tasks.append(task)
 
         return task
 
-    def _send_periodic_internal(self, msgs, period, duration=None):
+    def _send_periodic_internal(
+        self,
+        msgs: Union[Sequence[can.Message], can.Message],
+        period: float,
+        duration: Optional[float] = None,
+    ) -> can.broadcastmanager.CyclicSendTaskABC:
         """Default implementation of periodic message sending using threading.
 
         Override this method to enable a more efficient backend specific approach.
@@ -275,7 +293,7 @@ def stop_all_periodic_tasks(self, remove_tasks=True):
         if remove_tasks:
             self._periodic_tasks = []
 
-    def __iter__(self):
+    def __iter__(self) -> Iterator[can.Message]:
         """Allow iteration on messages as they are received.
 
             >>> for msg in bus:
@@ -291,18 +309,20 @@ def __iter__(self):
                 yield msg
 
     @property
-    def filters(self):
+    def filters(self) -> Optional[Iterable[dict]]:
         """
         Modify the filters of this bus. See :meth:`~can.BusABC.set_filters`
         for details.
         """
         return self._filters
 
     @filters.setter
-    def filters(self, filters):
+    def filters(self, filters: Optional[Iterable[Dict[str, Union[bool, int, str]]]]):
         self.set_filters(filters)
 
-    def set_filters(self, filters=None):
+    def set_filters(
+        self, filters: Optional[Iterable[Dict[str, Union[bool, int, str]]]] = None
+    ):
         """Apply filtering to all messages received by this Bus.
 
         All messages that match at least one filter are returned.
@@ -327,7 +347,9 @@ def set_filters(self, filters=None):
         self._filters = filters or None
         self._apply_filters(self._filters)
 
-    def _apply_filters(self, filters):
+    def _apply_filters(
+        self, filters: Optional[Iterable[Dict[str, Union[bool, int, str]]]]
+    ):
         """
         Hook for applying the filters to the underlying kernel or
         hardware if supported/implemented by the interface.
@@ -336,7 +358,7 @@ def _apply_filters(self, filters):
             See :meth:`~can.BusABC.set_filters` for details.
         """
 
-    def _matches_filters(self, msg):
+    def _matches_filters(self, msg: can.Message) -> bool:
         """Checks whether the given message matches at least one of the
         current filters. See :meth:`~can.BusABC.set_filters` for details
         on how the filters work.
@@ -388,7 +410,7 @@ def __exit__(self, exc_type, exc_val, exc_tb):
         self.shutdown()
 
     @property
-    def state(self):
+    def state(self) -> BusState:
         """
         Return the current state of the hardware
 
@@ -397,7 +419,7 @@ def state(self):
         return BusState.ACTIVE
 
     @state.setter
-    def state(self, new_state):
+    def state(self, new_state: BusState):
         """
         Set the new state of the hardware
 
@@ -406,7 +428,7 @@ def state(self, new_state):
         raise NotImplementedError("Property is not implemented.")
 
     @staticmethod
-    def _detect_available_configs():
+    def _detect_available_configs() -> Iterator[dict]:
         """Detect all configurations/channels that this interface could
         currently connect with.