Object Pass by reference

Projects Programming
1

Fairly new to Arduino, and its been a few years since c++, but....

I get the error messages below. It doesn't say what line but it seems to be complaining about my transition() function:

Traffic:-1: error: variable or field 'transition' declared void
Traffic:-1: error: 'TLight' was not declared in this scope
Traffic:-1: error: 'toRed' was not declared in this scope
Traffic:-1: error: 'TLight' was not declared in this scope
Traffic:-1: error: 'toGreen' was not declared in this scope
Traffic:-1: error: expected primary-expression before 'int'

Does the arduino version of the compiler support pass by reference, or, what am I missing...

Thanks!! Having a great time with this with my nieces!

John

class TLight {
private:
int rP,yP,gP;
int doubleRedP;
public:
TLight(int red, int yellow, int green, int extraRed)
{
rP = red; yP = yellow; gP = green; doubleRedP = extraRed;
pinMode(rP, OUTPUT);
pinMode(yP, OUTPUT);
pinMode(gP, OUTPUT);
}

TLight(int red, int yellow, int green)
{
rP = red; yP = yellow; gP = green; doubleRedP = -1;
pinMode(rP, OUTPUT);
pinMode(yP, OUTPUT);
pinMode(gP, OUTPUT);
}

void red() { set(HIGH, LOW, LOW); }
void yellow(){ set(LOW, HIGH, LOW); }
void green() { set(LOW, LOW, HIGH); }

private:
void set(int rV, int yV, int gV){
digitalWrite(rP, rV);
digitalWrite(yP, yV);
digitalWrite(gP, gV);
if (doubleRedP >= 0)
digitalWrite(doubleRedP, rV);
}
};

TLight t1( 9, 11, 13);
//TLight t2( 5,6,7);

void transition( TLight & toRed, TLight& toGreen, int yellowDelay)
{
toRed.yellow();
delay(yellowDelay);
toRed.red();
toGreen.green();
}

// The setup() method runs once, when the sketch starts
void setup() {
t1.green();
// t2.red();
}

void loop()
{
//transition(t1, t2, 1000); delay(4000);
//transition(t2, t1, 1000); delay(4000);
}

2

It's a problem with the IDE, try to author your class and your transition function in a different tab :slight_smile:

3

I'm not sure what the IDE does and doesn't do for me w.r.t. header files, etc.

Now I have Traffic.pde:

TLight t1( 9, 11, 13);
//TLight t2( 5,6,7);

void setup() {
t1.green();
// t2.red();
}
void loop()
{
//transition(t1, t2, 1000); delay(4000);
//transition(t2, t1, 1000); delay(4000);
}

and TLight.pde in a separate "tab":

class TLight {
private**:**
int rP,yP,gP;
int doubleRedP;
public**:**
TLight(int red, int yellow, int green, int extraRed)
{
rP = red;
yP = yellow;
gP = green;
doubleRedP = extraRed;
pinMode(rP, OUTPUT);
pinMode(yP, OUTPUT);
pinMode(gP, OUTPUT);
}

TLight(int red, int yellow, int green)
{
rP = red;
yP = yellow;
gP = green;
doubleRedP = -1;
pinMode(rP, OUTPUT);
pinMode(yP, OUTPUT);
pinMode(gP, OUTPUT);
}

void red() {
set(HIGH, LOW, LOW);
}
void yellow(){
set(LOW, HIGH, LOW);
}
void green() {
set(LOW, LOW, HIGH);
}

private**:**
void set(int rV, int yV, int gV){
digitalWrite(rP, rV);
digitalWrite(yP, yV);
digitalWrite(gP, gV);
if (doubleRedP >= 0)
digitalWrite(doubleRedP, rV);
}
};

void transition( TLight & toRed, TLight& toGreen, int yellowDelay)
{
toRed.yellow();
delay(yellowDelay);
toRed.red();
toGreen.green();
}

And I still get:

Traffic:-1: error: variable or field 'transition' declared void
Traffic:-1: error: 'TLight' was not declared in this scope
Traffic:-1: error: 'toRed' was not declared in this scope
Traffic:-1: error: 'TLight' was not declared in this scope
Traffic:-1: error: 'toGreen' was not declared in this scope
Traffic:-1: error: expected primary-expression before 'int'
Traffic:0: error: 'TLight' does not name a type
Traffic.cpp: In function 'void setup()':
Traffic:4: error: 't1' was not declared in this scope

4

Ok, it took me an hour to figure out that I need to include "WProgram.h" in my other file. So for the sake of posterity, here is the configuration:
Traffic ("Main Tab"):

#include "TLight.h"

TLight t1( 9, 11, 13);
TLight t2( 5,6,7);

void setup()
{
t1.green();
t2.red();
}
void loop()
{
transition(t1, t2, 1000); delay(4000);
transition(t2, t1, 1000); delay(4000);
}

void transition( TLight & toRed, TLight& toGreen, int yellowDelay)
{
toRed.yellow();
delay(yellowDelay);
toRed.red();
toGreen.green();
}

TLight.h:

#include "WProgram.h"

class TLight {
.... etc, as before
};

Cheers,
John

5

Calling core functions in an object constructor can cause serious problems...

TLight(int red, int yellow, int green)
{
...
pinMode(rP, OUTPUT);
pinMode(yP, OUTPUT);
pinMode(gP, OUTPUT);
}

Object constructors are called before the hardware has been initialized. Add a begin function that initializes the hardware then call begin in setup. In other words, use Serial as an example of how to do things correctly.