How to Create a reference to an External Print object

Question

Right now I have an object:

class Dog
{
  public:
    Dog(uint8_t I2c, Stream& feedback);
    void Speak();
  private:
    uint8_t _I2c;
    Stream& _output;
};

Dog::Dog(uint8_t I2c, Stream& feedback):_output(feedback),_I2c(I2c){}

Dog::Speak(){
_output.println("Hi There.");
}

That is currently constructed in my sketch via:

Dog Dug([I2cPort], Serial);

How can I modify my class so that to be compatible with taking either a Serial object or an LCD display (using Adafruit's RGB LCD library )?

Eg:

Adafruit_RGBLCDShield lcd = Adafruit_RGBLCDShield();
Dog Dug([I2cPort], Serial);
Dog Sam([I2cPort], lcd);

Additional info:

The LCD in question is mostly used as a UI display in its own library this library refreshes the display every 1.5 sec. As information from speak(); and the UI have similar priority, it is acceptable if one instantly overwrites the other.

I am open to solutions that involve modifying the construction of Dog the only requirement is that I need to be able to indicate print("[something]"); in the Dog.cpp

I'm interested in asking this question on the Arduino SE as I believe there are differences in how you would approach this if the problem was on a traditional computer.

it is not a buffer. only a reference – Juraj Sep 12 '18 at 16:36 — Juraj, Sep 12 '18 at 16:36
Noted, edited the question for clarity. – ATE-ENGE Sep 12 '18 at 16:39 — ATE-ENGE, Sep 12 '18 at 16:39
nice. now you put the answer into the questions title :-) – Juraj Sep 12 '18 at 16:40 — Juraj, Sep 12 '18 at 16:40
And just like that, it works. Thanks for the magic. – ATE-ENGE Sep 12 '18 at 17:02 — ATE-ENGE, Sep 12 '18 at 17:02

score 1 · Accepted Answer · answered Sep 12 '18 at 16:28

1

If your class is only writing to the stream you probably want to have your class take a Print object instead of a Stream object.

The Adafruit library inherits from Print.

answered Sep 12 '18 at 16:28

Craig

2,110
9
11

That can change, I only need this line for feedback to either my COM port (Serial) or to the LCD. – ATE-ENGE Sep 12 '18 at 16:40
both are derived from Print class. https://arduino.stackexchange.com/questions/52563/syslogappender-for-log4esp/52575#52575 – Juraj Sep 12 '18 at 16:41

How to Create a reference to an External Print object

1 Answers1