Add type annotations, updates to documentation

adafruit_aws_iot.py

@@ -26,6 +26,13 @@
 import json
 from adafruit_minimqtt.adafruit_minimqtt import MMQTTException
 
+try:
+    from typing import Optional, Type, Union
+    from types import TracebackType
+    from adafruit_minimqtt.adafruit_minimqtt import MQTT
+except ImportError:
+    pass
+
 __version__ = "0.0.0-auto.0"
 __repo__ = "https://github.com/adafruit/Adafruit_CircuitPython_AWS_IOT.git"
 
@@ -40,13 +47,13 @@ class AWS_IOT_ERROR(Exception):
 class MQTT_CLIENT:
     """Client for interacting with Amazon AWS IoT MQTT API.
 
-    :param MiniMQTT mmqttclient: Pre-configured MiniMQTT Client object.
+    :param ~MQTT.MQTT mmqttclient: Pre-configured MiniMQTT Client object.
     :param int keep_alive: Optional Keep-alive timer interval, in seconds.
                           Provided interval must be 30 <= keep_alive <= 1200.
 
     """
 
-    def __init__(self, mmqttclient, keep_alive=30):
+    def __init__(self, mmqttclient: MQTT, keep_alive: int = 30) -> None:
         if "MQTT" in str(type(mmqttclient)):
             self.client = mmqttclient
         else:
@@ -88,18 +95,23 @@ def __init__(self, mmqttclient, keep_alive=30):
         self.client.on_unsubscribe = self._on_unsubscribe_mqtt
         self.connected_to_aws = False
 
-    def __enter__(self):
+    def __enter__(self) -> "MQTT_CLIENT":
         return self
 
-    def __exit__(self, exception_type, exception_value, traceback):
+    def __exit__(
+        self,
+        exception_type: Optional[Type[type]],
+        exception_value: Optional[BaseException],
+        traceback: Optional[TracebackType],
+    ) -> None:
         self.disconnect()
 
     @property
-    def is_connected(self):
+    def is_connected(self) -> bool:
         """Returns if MQTT_CLIENT is connected to AWS IoT MQTT Broker"""
         return self.connected_to_aws
 
-    def disconnect(self):
+    def disconnect(self) -> None:
         """Disconnects from Amazon AWS IoT MQTT Broker and de-initializes the MiniMQTT Client."""
         try:
             self.client.disconnect()
@@ -114,15 +126,16 @@ def disconnect(self):
         self.on_unsubscribe = None
         self.client.deinit()
 
-    def reconnect(self):
+    def reconnect(self) -> None:
         """Reconnects to the AWS IoT MQTT Broker"""
         try:
             self.client.reconnect()
         except MMQTTException as error:
             raise AWS_IOT_ERROR("Error re-connecting to AWS IoT:", error) from error
 
-    def connect(self, clean_session=True):
+    def connect(self, clean_session: bool = True) -> None:
         """Connects to Amazon AWS IoT MQTT Broker with Client ID.
+
         :param bool clean_session: Establishes a clean session with AWS broker.
 
         """
@@ -134,9 +147,12 @@ def connect(self, clean_session=True):
 
     # MiniMQTT Callback Handlers
     # pylint: disable=not-callable, unused-argument
-    def _on_connect_mqtt(self, client, userdata, flag, ret_code):
+    def _on_connect_mqtt(
+        self, client: MQTT, userdata: str, flag: int, ret_code: int
+    ) -> None:
         """Runs when code calls on_connect.
-        :param MiniMQTT client: MiniMQTT client object.
+
+        :param ~MQTT.MQTT client: MiniMQTT client object.
         :param str user_data: User data from broker
         :param int flag: QoS flag from broker.
         :param int ret_code: Return code from broker.
@@ -148,9 +164,12 @@ def _on_connect_mqtt(self, client, userdata, flag, ret_code):
             self.on_connect(self, userdata, flag, ret_code)
 
     # pylint: disable=not-callable, unused-argument
-    def _on_disconnect_mqtt(self, client, userdata, flag, ret_code):
+    def _on_disconnect_mqtt(
+        self, client: MQTT, userdata: str, flag: int, ret_code: int
+    ) -> None:
         """Runs when code calls on_disconnect.
-        :param MiniMQTT client: MiniMQTT client object.
+
+        :param ~MQTT.MQTT client: MiniMQTT client object.
         :param str user_data: User data from broker
         :param int flag: QoS flag from broker.
         :param int ret_code: Return code from broker.
@@ -162,9 +181,10 @@ def _on_disconnect_mqtt(self, client, userdata, flag, ret_code):
             self.on_connect(self, userdata, flag, ret_code)
 
     # pylint: disable=not-callable
-    def _on_message_mqtt(self, client, topic, payload):
+    def _on_message_mqtt(self, client: MQTT, topic: str, payload: str) -> None:
         """Runs when the client calls on_message.
-        :param MiniMQTT client: MiniMQTT client object.
+
+        :param ~MQTT.MQTT client: MiniMQTT client object.
         :param str topic: MQTT broker topic.
         :param str payload: Payload returned by MQTT broker topic
 
@@ -173,26 +193,36 @@ def _on_message_mqtt(self, client, topic, payload):
             self.on_message(self, topic, payload)
 
     # pylint: disable=not-callable
-    def _on_subscribe_mqtt(self, client, user_data, topic, qos):
+    def _on_subscribe_mqtt(
+        self, client: MQTT, user_data: str, topic: int, qos: int
+    ) -> None:
         """Runs when the client calls on_subscribe.
 
-        :param MiniMQTT client: MiniMQTT client object.
+        :param ~MQTT.MQTT client: MiniMQTT client object.
         :param str user_data: User data from broker
         :param str topic: Desired MQTT topic.
-        param int qos: Quality of service level for topic, from broker.
+        :param int qos: Quality of service level for topic, from broker.
 
         """
         if self.on_subscribe is not None:
             self.on_subscribe(self, user_data, topic, qos)
 
     # pylint: disable=not-callable
-    def _on_unsubscribe_mqtt(self, client, user_data, topic, pid):
-        """Runs when the client calls on_unsubscribe."""
+    def _on_unsubscribe_mqtt(
+        self, client: MQTT, user_data: str, topic: str, pid: int
+    ) -> None:
+        """Runs when the client calls on_unsubscribe.
+
+        :param ~MQTT.MQTT client: MiniMQTT client object.
+        :param str user_data: User data from broker
+        :param str topic: Desired MQTT topic.
+        :param int pid: Process ID.
+        """
         if self.on_unsubscribe is not None:
             self.on_unsubscribe(self, user_data, topic, pid)
 
     # MiniMQTT Network Control Flow
-    def loop(self):
+    def loop(self) -> None:
         """Starts a synchronous message loop which maintains connection with AWS IoT.
         Must be called within the keep_alive timeout specified to init.
         This method does not handle network connection/disconnection.
@@ -207,28 +237,28 @@ def loop(self):
         if self.connected_to_aws:
             self.client.loop()
 
-    def loop_forever(self):
+    def loop_forever(self) -> None:
         """Begins a blocking, asynchronous message loop.
         This method handles network connection/disconnection.
-
         """
         if self.connected_to_aws:
             self.client.loop_forever()
 
     @staticmethod
-    def validate_topic(topic):
+    def validate_topic(topic: str) -> None:
         """Validates if user-provided pub/sub topics adhere to AWS Service Limits.
         https://docs.aws.amazon.com/general/latest/gr/aws_service_limits.html
-        :param str topic: Desired topic to validate
 
+        :param str topic: Desired topic to validate
         """
         assert hasattr(topic, "split"), "Topic must be a string"
         assert len(topic) < 256, "Topic must be less than 256 bytes!"
         assert len(topic.split("/")) <= 9, "Topics are limited to 7 forward slashes."
 
     # MiniMQTT Pub/Sub Methods, for usage with AWS IoT
-    def subscribe(self, topic, qos=1):
+    def subscribe(self, topic: str, qos: int = 1) -> None:
         """Subscribes to an AWS IoT Topic.
+
         :param str topic: MQTT topic to subscribe to.
         :param int qos: Desired topic subscription's quality-of-service.
 
@@ -237,14 +267,16 @@ def subscribe(self, topic, qos=1):
         self.validate_topic(topic)
         self.client.subscribe(topic, qos)
 
-    def publish(self, topic, payload, qos=1):
+    def publish(
+        self, topic: str, payload: Union[str, float, bytes], qos: int = 1
+    ) -> None:
         """Publishes to a AWS IoT Topic.
+
         :param str topic: MQTT topic to publish to.
-        :param str payload: Data to publish to topic.
-        :param int payload: Data to publish to topic.
-        :param float payload: Data to publish to topic.
-        :param json payload: JSON-formatted data to publish to topic.
-        :param int qos: Quality of service level for publishing.
+        :param payload: Data to publish to topic.  Must be able to be converted
+            to a string using ``str()``
+        :type payload: str|float|bytes
+        :param int qos: Quality of service level for publishing
 
         """
         assert qos < 2, "AWS IoT does not support publishing with QoS 2."
@@ -255,35 +287,37 @@ def publish(self, topic, payload, qos=1):
 
     # AWS IoT Device Shadow Service
 
-    def shadow_get_subscribe(self, qos=1):
+    def shadow_get_subscribe(self, qos: int = 1) -> None:
         """Subscribes to  device's shadow get response.
-        :param int qos: Optional quality of service level.
 
+        :param int qos: Optional quality of service level.
         """
         self.client.subscribe(self.shadow_topic + "/get/#", qos)
 
-    def shadow_subscribe(self, qos=1):
+    def shadow_subscribe(self, qos: int = 1) -> None:
         """Subscribes to all notifications on the device's shadow update topic.
-        :param int qos: Optional quality of service level.
 
+        :param int qos: Optional quality of service level.
         """
         self.client.subscribe(self.shadow_topic + "/update/#", qos)
 
-    def shadow_update(self, document):
+    def shadow_update(self, document: str):
         """Publishes a request state document to update the device's shadow.
-        :param json state_document: JSON-formatted state document.
 
+        :param str state_document: JSON-formatted state document string.
         """
         self.client.publish(self.shadow_topic + "/update", document)
 
-    def shadow_get(self):
+    def shadow_get(self) -> None:
         """Publishes an empty message to shadow get topic to get the device's shadow."""
+
         self.client.publish(
             self.shadow_topic + "/get", json.dumps({"message": "ignore"})
         )
 
-    def shadow_delete(self):
+    def shadow_delete(self) -> None:
         """Publishes an empty message to the shadow delete topic to delete a device's shadow"""
+
         self.client.publish(
             self.shadow_topic + "/delete", json.dumps({"message": "delete"})
         )