Millis() Instead of Delay Library Questions

Using Arduino Programming Questions
9

I changed my code to the following:
Easy.cpp:

#if ARDUINO >= 100
#include "Arduino.h"
#else
#include "WProgram.h"
#endif

#include "Easy.h"
Routine::Routine(){
  go = true;
  prev = 0;
  prev2 = 0;
  prev_us = 0;
  prev_us2 = 0;
}
void Routine::begin(unsigned long interval, void (*g)()){
  //static unsigned long prev = 0;
  if (millis() - prev >= interval && go){
    g();
    prev = millis();
  }
}
void Routine::begin(unsigned long interval, void (*g)(), word times){
  //static unsigned long prev = 0;
  static word counter = 0;
  if (millis() - prev2 >= interval && go && counter < times){
    g();
    prev2 = millis();
    counter++;
  }
}
void Routine::end(){
  go = false;
}
void Routine::begin_us(unsigned long interval, void (*g)()){
  //static unsigned long prev = 0;
  if (micros() - prev_us >= interval && go){
    g();
    prev_us = micros();
  }
}
void Routine::begin_us(unsigned long interval, void (*g)(), unsigned long times){
  //static unsigned long prev = 0;
  static unsigned long counter = 0;
  if (micros() - prev_us2 >= interval && go && counter < times){
    g();
    prev_us2 = micros();
    counter++;
  }
}
void Routine::restart(){
  go = true;
}

Easy.h:

#ifndef Easy_h
#define Easy_h

#if ARDUINO >= 100
#include "Arduino.h"
#else
#include "WProgram.h"
#endif

class Routine{
  public:
  Routine();
  void begin(unsigned long interval, void (*g)());
  void begin(unsigned long interval, void (*g)(), word times);
  void end();
  void restart();
  void begin_us(unsigned long interval, void (*g)());
  void begin_us(unsigned long interval, void (*g)(), unsigned long times);
  private:
  boolean go;
  unsigned long prev;
  unsigned long prev2;
  unsigned long prev_us;
  unsigned long prev_us2;
};

I used 4 private variables for the begin functions. Now it will multitask!