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edited Sep 6, 2019 at 15:50

Thanks to all for the clues; I'm an old-time c/c++ programmer, but must have slept through the 'lambda function' class ;-).

To help my somewhat calcified brain, is it functionally equivalent (if more clunky) to write the above snippet as shown below with the handler functions 'unchained'?

    ArduinoOTA.onStart
([]() //lambda function 
    { 
        String type;
        if (ArduinoOTA.getCommand() == U_FLASH)
            type = "sketch";
        else // U_SPIFFS
            type = "filesystem";

        // NOTE: if updating SPIFFS this would be the place to unmount SPIFFS using SPIFFS.end()
        Serial.println("Start updating " + type);
    }
);

ArduinoOTA.onEnd
([]() //lambda function
    {
        Serial.println("\nEnd");
    }
);

ArduinoOTA.onProgress
([](unsigned int progress, unsigned int total) //lambda func with arguments 
    {
        Serial.printf("Progress: %u%%\r", (progress / (total / 100)));
    }
);

ArduinoOTA.onError
([](ota_error_t error) //lambda func with arguments
    {
        Serial.printf("Error[%u]: ", error);
        if (error == OTA_AUTH_ERROR) Serial.println("Auth Failed");
        else if (error == OTA_BEGIN_ERROR) Serial.println("Begin Failed");
        else if (error == OTA_CONNECT_ERROR) Serial.println("Connect Failed");
        else if (error == OTA_RECEIVE_ERROR) Serial.println("Receive Failed");
        else if (error == OTA_END_ERROR) Serial.println("End Failed");
    }
);

TIA,

Frank

Thanks to all for the clues; I'm an old-time c/c++ programmer, but must have slept through the 'lambda function' class ;-).

To help my somewhat calcified brain, is it functionally equivalent (if more clunky) to write the above snippet as shown below with the handler functions 'unchained'?

    ArduinoOTA.onStart
([]() //lambda function 
    { 
        String type;
        if (ArduinoOTA.getCommand() == U_FLASH)
            type = "sketch";
        else // U_SPIFFS
            type = "filesystem";

        // NOTE: if updating SPIFFS this would be the place to unmount SPIFFS using SPIFFS.end()
        Serial.println("Start updating " + type);
    }
);

ArduinoOTA.onEnd
([]() //lambda function
    {
        Serial.println("\nEnd");
    }
);

ArduinoOTA.onProgress
([](unsigned int progress, unsigned int total) //lambda func with arguments 
    {
        Serial.printf("Progress: %u%%\r", (progress / (total / 100)));
    }
);

ArduinoOTA.onError
([](ota_error_t error) //lambda func with arguments
    {
        Serial.printf("Error[%u]: ", error);
        if (error == OTA_AUTH_ERROR) Serial.println("Auth Failed");
        else if (error == OTA_BEGIN_ERROR) Serial.println("Begin Failed");
        else if (error == OTA_CONNECT_ERROR) Serial.println("Connect Failed");
        else if (error == OTA_RECEIVE_ERROR) Serial.println("Receive Failed");
        else if (error == OTA_END_ERROR) Serial.println("End Failed");
    }
);

TIA,

Frank

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asked Sep 4, 2019 at 14:57

starship15

Help with function template syntax

I am trying to understand the following code snippet from the Espressif OTABasic example for the ESP32 wireless/BT module (see this repository for the full code).

 ArduinoOTA
.onStart([]() {
  String type;
  if (ArduinoOTA.getCommand() == U_FLASH)
    type = "sketch";
  else // U_SPIFFS
    type = "filesystem";

  // NOTE: if updating SPIFFS this would be the place to unmount SPIFFS using SPIFFS.end()
  Serial.println("Start updating " + type);
})
.onEnd([]() {
  Serial.println("\nEnd");
})
.onProgress([](unsigned int progress, unsigned int total) {
  Serial.printf("Progress: %u%%\r", (progress / (total / 100)));
})
.onError([](ota_error_t error) {
  Serial.printf("Error[%u]: ", error);
  if (error == OTA_AUTH_ERROR) Serial.println("Auth Failed");
  else if (error == OTA_BEGIN_ERROR) Serial.println("Begin Failed");
  else if (error == OTA_CONNECT_ERROR) Serial.println("Connect Failed");
  else if (error == OTA_RECEIVE_ERROR) Serial.println("Receive Failed");
  else if (error == OTA_END_ERROR) Serial.println("End Failed");
});

The initial 'ArduinoOTA' looks kinda like an implied 'with ArduinoOTA' statement, but I can't find anything like that in the reference documents. I know it has something to do with the way the function templates in 'ArduinoOTA.h', but it's beyond me to untangle the syntax.

May I buy a clue, please?

TIA,

Frank

esp32