Code (C++)

// Manager.h

#ifndef _MANAGER_h
#define _MANAGER_h

	#include "Arduino.h"




class ManagerClass
{
 public:
	template<typename T> void doSomething(T param);
};


extern ManagerClass Manager;

#endif




//manager.cpp
include "Manager.h"

template <typename T>
void ManagerClass::doSomething(T param)
{
	Serial.println(param);
}

ManagerClass Manager;







//sketch2.ino
#include "Manager.h"

void setup() {
	Serial.begin(115200);
}

// the loop function runs over and over again until power down or reset
void loop() {

	Manager.doSomething("123123");
}