Python avoid global variable while polling data

Question

I am writing an mqtt client, which is looping forever while collecting message data.

The array is currently global, but since this is considered bad practice I want to avoid that. However I am not sure how to call on_message with another parameter.

How can I avoid using array as a global variable?

   def on_message(client, userdata, msg):
        global array
        array.append(msg.payload)

   array = []
   client = mqtt.Client()
   client.on_connect = on_connect
   client.on_message = on_message
   client.connect("JOHN", 1883, 60)
   client.loop_forever()

EDIT: I followed CarloLobranos advice and am using userdata now as an input (as the API supports that). Thanks for all answers!

Answer 1

You can wrap everything in a function:

def mqtt_wrapper():
    array = []
    def on_message(client, userdata, msg):
        array.append(msg.payload)
    client = mqtt.Client()
    client.on_connect = on_connect
    client.on_message = on_message
    client.connect("JOHN", 1883, 60)
    client.loop_forever()

mqtt_wrapper()