I want to inherit SPIFFS class to extend it for my methods. Is it possible?

Question

I have ESP32 project using Arduino framework and I have problem. I want to create my class, which would be inheriting from SPIFFS class. Just want to add readConfig method and use it in my project.

Is it possible?

I am using something like. SSDReader.h

#pragma once
#include <Arduino.h>
#include <SPIFFS.h>
#include <FS.h>

using namespace fs;
class SSDReader: public SPIFFSFS {
  public:
    void getConfig();

};

extern SSDReader ssd;

SSDReader.cpp

#include "SSDReader.h"

void SSDReader::getConfig() {

}

main.cpp

#pragma once
#include <Arduino.h>
#include "include/SSDReader.h“

void setup() {
  // Init SSDReader
  if (!ssd.begin()) {

  }
}

void loop() {

}

It compiles, but the ssd is then:

.pioenvs/esp32dev/src/main.cpp.o:(.literal._Z5setupv+0x10): undefined reference to `ssd'
collect2: error: ld returned 1 exit status
*** [.pioenvs/esp32dev/firmware.elf] Error 1

Thanks, Regards, Petr Sourek

Answer 1

Thanks to KIIV I have been able to edit my code like this.

SSDReader.h

#pragma once
#include <Arduino.h>
#include <SPIFFS.h>

using namespace fs;
class SSDReader : public SPIFFSFS {
  public:
    SSDReader() : SPIFFSFS{ SPIFFS } { };
    void getConfig();

  protected:
};

SSDReader.cpp

#include "SSDReader.h"

//SSDReader::SSDReader() {}


void SSDReader::getConfig() {

}

main.cpp

#include <Arduino.h>
#include "include/SSDReader.h"
//#include "include/Display.h"

// Variables
SSDReader ssd;
bool enableSerial = false;

//Display display;

void setup() {
  if (enableSerial)
    Serial.println(9600);

  // Init SSDReader
  if (!ssd.begin()) {

  }

}

void loop() {

}

And it works. Thank you very much. I am going to selfstudy more.