python - 将参数传递给 paho mqtt 回调

Question

我是 Python 新手，每次收到 MQTT 消息/主题时，我都会尝试运行一个控件来使 RGB LED 发出脉冲。因此，我创建了一个对象 threadObj 来运行线程并循环脉冲动画。

我面临的问题是我不知道如何将对象实例传递给 on_message mqtt 回调。我一直在寻找部分功能应用程序，但现在我不确定这是否是正确的方法。

这是主要脚本:

from P9813 import P9813
from safeGPIO import safeGPIO as GPIO
import json
from math import ceil
import os
import threading
import queue
import sys
import subprocess
import threading
import time
from functools import partial
from ledPulse import ledPulse
import paho.mqtt.client as mqtt

def on_connect(client, userdata, flags, rc):
    print("Connected to {0} with result code {1}".format(HOST, rc))
    # Subscribe to any hotword topic --- old code:   # client.subscribe("hermes/hotword/default/detected")
    client.subscribe("hermes/hotword/#")

    # Subscribe to any topic starting with 'hermes/intent/'
    client.subscribe('hermes/intent/#')

def on_message(client, userdata, msg):

    print("- Message received on topic {0}: {1}".format(msg.topic, msg.payload))
    print('* ledPulse instance count {0} nameid {1}'.format(ledPulse.instance_count, threadObj))

    if msg.topic == 'hermes/hotword/default/detected':
        print("Wakeword detected! Wakeword light!")
        #Wakeword light

        print('ledPulseThread.Status -> ON and status {0}'.format(threadObj.status))
        threadObj.Status = "ON"  # T.StreamV could be modified to run at creation and wait for this to change to "ON"
        threadObj.msgTopic = msg.topic
        threadObj.ledDriver = ledDriver
        threadObj.ledColor = LEDS_CYAN
        #threadObj.daemon = True
        threadObj.ledPulseThread.start()  # this calls the T.StreamV function in a separate thread

    if msg.topic == 'hermes/intent/mywai:ShowMarketplace':
        # intent ShowMarketplace light
        print("Intent detected! ShowMarketplace light!")
        ledDriver[0] = LEDS_GREEN
        ledDriver.write()

    if msg.topic == 'hermes/hotword/toggleOn':
        # light for hotword toggled-on
        threadObj.ledColor = LEDS_WARM_WHITE
        threadObj.Status = "OFF"
        print('status ', threadObj.Status)
        print('T.Status -> "OFF"')
        print("Intent detected!  Hotword ended!")
        ledDriver[0] = LEDS_WARM_WHITE
        ledDriver.write()
        #threadObj.ledPulseThread.terminate()  # this calls the T.StreamV function in a separate thread

#########################################################################
# MAIN
#########################################################################
if __name__ == '__main__':
    #main()    
    HOST = 'localhost'
    PORT = 1883
    gpio = GPIO()
    gpio.cleanup()

    # Construct the object
    ledDriver = P9813(32, 33)
    # Create led (R,G,B) list
    leds = [[0, 0, 0]]

    # Define color constants
    #              [R,G,B]
    LED_STRENGTH = 100
    LEDS_OFF = [0, 0, 0]
    LEDS_RED = [LED_STRENGTH, 0, 0]
    LEDS_GREEN = [0, LED_STRENGTH, 0]
    LEDS_BLUE = [0, 0, LED_STRENGTH]
    LEDS_YELLOW = [LED_STRENGTH, LED_STRENGTH, 0]
    LEDS_MAGENTA = [LED_STRENGTH, 0, LED_STRENGTH]
    LEDS_CYAN = [0, LED_STRENGTH, LED_STRENGTH]
    LEDS_WHITE = [LED_STRENGTH, LED_STRENGTH, LED_STRENGTH]
    LEDS_WARM_WHITE = [210, 155, 35]

    # Default light is warm white
    #ledDriver[0] = LEDS_WARM_WHITE
    #ledDriver.write()

    # t1 = threading.Thread(target=loop_test, args=(deca,))
    # t1.start()

    threadObj = ledPulse(ledDriver)  # our thread is actually created here, but is hasn't started yet

    client = mqtt.Client()
    client.on_connect = on_connect
    #client.on_message = on_message
    client.on_message = partial(on_message, threadObj) #https://stackoverflow.com/questions/15331726/how-does-the-functools-partial-work-in-python

    client.connect(HOST, PORT, 60)
    client.loop_forever()

    # Ask the user repeatedly for LED brightness setting
    try:
        while (True):
            str = raw_input("Input R, G, B [Enter] or Ctrl-C to quit. R, G, B range from 0 - 255: ")
            leds[0] = list(map(int, str.split(",")))
            print(leds[0])
            ledDriver[0] = leds[0]
            ledDriver.write()
    except KeyboardInterrupt:
        print("\r")
    except:
        print(str)

    # Turn off LEDs before we quit
    leds[0] = [0, 0, 0]
    ledDriver[0] = leds[0]
    ledDriver.write()

ledPulse 类:

import threading
import time

class ledPulse(object):

    instance_count = 0 #count how many istance of the class are created
    def __init__(self, ledDriver):
        self.status = "OFF"
        self.ledPulseThread = threading.Thread(target=self.ledPulseThread)  # create a thread for our streamV function
        self.ledColor = [30, 40, 50]
        self.ledDriver = ledDriver
        self.msgTopic = ""
        self.counter = 0
        ledPulse.instance_count += 1

    def ledPulseThread(self):
        print("starting thread")
        while self.status == "ON":
            print("nonstop | status = ", self.Status)
            self.ledDriver[0] = [0, 0, 0]
            self.ledDriver.write()
            time.sleep(0.2)
            print("{0} sec | color {2} | driver {3} | instance {4} | deca  {1}".format(self.counter, self.msgTopic, self.ledColor, self.ledDriver.write(), ledPulse.instance_count ))
            self.ledDriver[0] = self.ledColor
            self.ledDriver.write()
            time.sleep(0.2)
            self.counter = self.counter + 1
        print("stopping thread")
        self.counter = 0
        #raise SystemExit

Answer 1

将对象实例作为值放入字典中(或者任何可变对象，例如列表，如果您想更改回调中的值并查看主代码中反射(reflect)的更改)，然后将对象实例作为实例化 MQTT 客户端时的 userdata。例如:

client_userdata = {'myobject':threadObj}
client = mqtt.Client(userdata=client_userdata)

在 on_message 回调中，您可以在 userdata 变量中访问此字典。

userdata['myobject'] <- this is your threadObj