Mutator is not working

Hi,
This is my first post,

I’ve been having trouble with a mutator in my project. I’ve been doing some research and the most I could find was a solution using references (which I included in my code). However, this didn’t work. My project is a dispenser for dog food, I’m using OOP where I have 3 classes. The main class, Menu class, and Switch class. Menu class is where I use the LCD screen and Switch class is where I define the functionality of the switches. I’m having trouble in Menu class where I have the function setMenu(Switch right); which is a menu where the user is supposed to set the times that is wanted to dispense food. The if loop that I’m using to send a message when the user wants to save time (with a long press) is staying true regardless of the mutator, therefore the message stays looped indefinitely. Why is the mutator not working?

Thanks so much in advance for your help

//Menu class
#include "Menu.h"

void Menu::setMenu(Switch right)
{
  //initialize right switch
  right.pressed();

  //code for setMenu, not relevant to my issue

  //save the time and send message
  if (right.getLongState()) //getter
  {
    clearScreen(); //function to clear the screen
    messageTime = millis() + 1500;

    while (millis() < messageTime)
    {
      lcd.setCursor(0, 0);
      lcd.print("Time Saved");
    }
    clearScreen();
    right.setLongState(false); //mutator
  }
}
//Switch class
#include "Switch.h"

//getter (accessor)
bool& Switch::getLongState() {
  return longState;
}

//setter (mutator)
void Switch::setLongState(bool l)
{
  longState = l;
  return;
}

//function for the functionalities of the switches (short press, counter, and long press with debouncing)
void Switch::pressed()
{
  byte reading = digitalRead(pin);

  if (reading != lastState)
  {
    lastDebounceTime = millis();
  }

  if ((millis() - lastDebounceTime) > debounceDelay)
  {
    if (reading != currentState)
    {
      currentState = reading;

      if (currentState)
      {
        pressedTime = millis();
        isPressing = true;
        isLongDetected = false;
      }
      else
      {
        isPressing = false;
        releasedTime = millis();

        long pressDuration = releasedTime - pressedTime;

        if (pressDuration < shortPressTime)
        {
          Serial.println("Short press");
          shortState = ! shortState;

          count++;

          if (count > 1)
            count = 0;
        }
      }
    }
  }

  if (isPressing == true && isLongDetected == false)
  {
    long pressDuration = millis() - pressedTime;

    if (pressDuration > longPressTime)
    {
      Serial.println("Long press");
      isLongDetected = true;
      longState = ! longState;
    }
  }
  lastState = reading;
}

Very few Arduino users use classes overtly. (They are hidden behind the IDE).

Is this a school project?
Is there a reason you want to do this the hard way?

And, what the heck is a "mutator"? Is this a feature of C++ that has somehow escaped my five years experience programming Arduinos?

I have no idea what a mutator is but I'm sorry to hear yours doesn't work. Can you send it back and get a replacement?

Steve

I've never heard them called that but wikipedia says this:

In computer science, a mutator method is a method used to control changes to a variable. They are also widely known as setter methods. Often a setter is accompanied by a getter (also known as an accessor), which returns the value of the private member variable.

Why does getLongState return a reference, rather than just a value? It makes no sense, especially for a getter, whose sole purpose is to LIMIT access to the variable.

I think the problem is that your "Switch" object is being passed by value. That means it makes a copy of the object. You are setting a value in the copy, not in the original. Try:

void Menu::setMenu(Switch &right)
{
  //initialize right switch
  right.pressed();

The '&' in "Switch &right" makes it a 'pass by reference' argument and a pointer to the original object is passed. Then when you call "setLongState()" it will modify the original object and not just the copy that was passed.

SteveMann:
Very few Arduino users use classes overtly. (They are hidden behind the IDE).

Is this a school project?
Is there a reason you want to do this the hard way?

And, what the heck is a "mutator"? Is this a feature of C++ that has somehow escaped my five years experience programming Arduinos?

It is a school project, I am required to use OOP to add complexity
A mutator or setter is a function that can change the value of a private variable, just like an accessor or getter is a function used to get the value of a private variable. :slight_smile:

johnwasser:
I think the problem is that your "Switch" object is being passed by value.

Nice catch.

johnwasser:
I think the problem is that your "Switch" object is being passed by value. That means it makes a copy of the object. You are setting a value in the copy, not in the original. Try:

void Menu::setMenu(Switch &right)

{
 //initialize right switch
 right.pressed();




The '&' in "Switch &right" makes it a 'pass by reference' argument and a pointer to the original object is passed. Then when you call "setLongState()" it will modify the original object and not just the copy that was passed.

Thanks, I tried that and it worked :slight_smile: I was placing the & in the wrong function

I am required to use OOP to add complexity

WOW! What kind of teacher says things like this?

-jim lee

jimLee:
WOW! What kind of teacher says things like this?

I'm thinking the reason for requiring the use of OOP programming techniques in a programming class assignment would be to teach OOP programming techniques. The "to add complexity" part is probably just Editorial Comment by @ferchi1809.

jimLee:
WOW! What kind of teacher says things like this?

-jim lee

A really old one? "I had to suffer OOP in college, now it's your turn".

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