I try to setup a mqtt client in python3. This is not the first time im doing this, however i came across a rather odd behaviour. When trying to call a function, which contains a bug, from one of the callback functions (on_connect or on_message), python does not throw an exception (at least it is not printed), it just stops there. I tied together a short example, that reproduces that behaviour.
Does someone has an idea?
import paho.mqtt.client as mqttimport re
import os.pathimport json
from termcolor import coloredclient = mqtt.Client()def func():test = 1 + "1"print("Should never reach that")def on_connect(client, userdata, flags, rc):"""Establishes connection to broker"""print("Connected to broker with result code " + str(rc))client.subscribe("test")def on_message(client,userdata,msg):print("Recieved message on " + msg.topic)params = {}if msg.topic == "test":print("Invoke func")func()if __name__ == "__main__":client.on_connect = on_connectclient.on_message = on_messageclient.connect("localhost",1883,60)client.loop_forever()
This is the output when sending a message to the topic "test":
Connected to broker with result code 0
Recieved message on test
Invoke func
When calling func() from main, i get the correct TypeError thrown. So something catches this exception in paho. I had a look at an olderproject (python2 though) and tried to recreate the behaviour. There the exception gets thrown correctly. What do i miss?
EDIT I can catch the exception by putting the func() call in a try block. How ever, it does not stop the execution of the program when not catched. I dont get why