added an example for using the attributes mechanism

examples/sensor_with_attrs.py

@@ -0,0 +1,38 @@
+#!/usr/bin/env python3
+"""Example of how to add attributes to any entity.
+
+In this particular example, a Sensor entity will be used. The main mechanisms
+can be used for all Things.
+
+The sensor is useless and nonsensical. But it should illustrate the difference
+between setting the state and setting the attributes.
+"""
+
+from ham import MqttManager
+from ham.sensor import Sensor
+from time import sleep
+import os
+
+
+MQTT_USERNAME = os.environ["MQTT_USERNAME"]
+MQTT_PASSWORD = os.environ["MQTT_PASSWORD"]
+MQTT_HOST = os.environ["MQTT_HOST"]
+
+
+class UserIDSensor(Sensor):
+    name = "UserID"
+    short_id = "uid"
+
+
+if __name__ == "__main__":
+    uid_sensor = UserIDSensor()
+    manager = MqttManager(MQTT_HOST, username=MQTT_USERNAME, password=MQTT_PASSWORD)
+    manager.add_thing(uid_sensor)
+
+    manager.start()
+
+    print("Entering an infinite loop, Ctrl+C multiple times to exit.")
+    while True:
+        uid_sensor.state = os.getuid()
+        uid_sensor.attributes = {"posix_name": os.getlogin()}
+        sleep(30)