class TerminalParser {
  public:
    virtual void whoAmI() {
      Serial.println(F("not implemented"));
    }
};

class HardwareDisplay : public TerminalParser {
    void whoAmI() {
      Serial.println(F("HardwareDisplay"));
    }
};

class SoftwareDisplay : public TerminalParser {
    void whoAmI() {
      Serial.println(F("SoftwareDisplay"));
    }
};

class PartialDisplay : public TerminalParser {
  // whoAmI is not implemented, the default function will be called in the parent class
};

HardwareDisplay h;
SoftwareDisplay s;
PartialDisplay p;

TerminalParser* myDisplays[] = {&h, &s, &p};

void setup() {
  Serial.begin(115200); Serial.println();
  for (auto & aDisplay : myDisplays) aDisplay->whoAmI();
}

void loop() {}