MQTT Callback error

having issue pubsubclient throwing compile errors in ide.

tried different versions of pubsubclient, (imroy , knolleary), ethernet version, nightly build of ide , still same.

code: [select]

pubsubclient client(server, 1883, callback, ethclient); throws 'callback' not declared in scope error.

looked online , tried variations of different sketches (example ones included) should work getting same error.

pretty stuck , tearing hair out cannot figure out issue appreciated.

// running arduino uno ethernet shield stacked on velleman ka-01 stacked on top of that. plan send mqtt messages openhab.

full script code:

code: [select]

#include <spi.h>
#include <ethernet.h>
#include <pubsubclient.h>

// set mac address
byte mac[] = { 0x90, 0xa2, 0xda, 0x0f, 0x5e, 0x69 };
 
// set fallback ip address if dhcp fails

// set broker server ip
byte server[] = { 192,168,0,40 };

ethernetclient ethclient;
pubsubclient client(server, 1883, callback, ethclient);

int soffitr;
int soffitg;
int soffitb;
int blue = 6;                   
int green = 5;
int red = 3;


void setup()
{
    // open serial communications
  serial.begin(9600);
 
    // start hard-coded address:
    serial.println("assigning static ip address:");
    ethernet.begin(mac, ip);
 
     serial.print("my address:");
  serial.println(ethernet.localip());
 
  // connect broker, give arduino name
  if (client.connect("arduino_led2")) {
   
    // publish message status topic
    client.publish("status/arduino_led","arduino led2 online");
   
    // listen messages on control topic
    client.subscribe("control/arduino_led/#");
   }
}

void loop()
{
  client.loop();
}

void callback(char* topic, byte* payload, unsigned int length) {
  // check messages on subscribed topics
  payload[length] = '\0';
  serial.print("topic: ");
  serial.println(string(topic));
 


  // check topic identify type of content
  if(string(topic) == "control/arduino_led/livingroom/color") {
    // convert payload string
    string value = string((char*)payload);
    //value.trim();
    serial.print (value);
    //serial.flush();
    // split string @ every "," , store in proper variable
    // convert final result integer
    soffitr = value.substring(0,value.indexof(',')).toint();
    soffitg = value.substring(value.indexof(',')+1,value.lastindexof(',')).toint();
    soffitb = value.substring(value.lastindexof(',')+1).toint();

    // print obtained values debugging
serial.print("red: ");
serial.println(soffitr);
//client.publish("status/arduino_led", soffitr);

serial.print("green: ");
serial.println(soffitg);
//client.publish("status/arduino_led", soffitg);

serial.print("blue: ");
serial.println(soffitb);
//client.publish("status/arduino_led/soffit/color/blue", int soffitb);
//serial.flush();
   
  analogwrite(green, soffitg);
  analogwrite(red, soffitr);
  analogwrite(blue, soffitb);
 
   while(serial.available())
  serial.read();
   
  }
}

perhaps need forward declaration of callback function?   see this stackoverflow question

eg (didnt try compile syntax may not totally correct)

code: [select]

ethernetclient ethclient;
void callback(char* topic, byte* payload, unsigned int length);

pubsubclient client(server, 1883, callback, ethclient);

or move code callback() above pubsubclient line.

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