Master enum for multiple enums

Using Arduino Programming Questions
1

Hello,

I want to use a master enum to be used with other enums. The compiler won't accept that.

Is there anyway to do that ?

This is the code I want to design:

// master button index
typedef enum : uint8_t {} FUNCTION_BUTTON_INDEX_T;

// electrical monitor and control
typedef enum : uint8_t {NO_BUTTON, CURRENT_READING, VOLTAGE_READING,
POWER_READING} ELECTRICAL_BUTTON_INDEX_T;

// motor control modes
typedef enum : uint8_t {NO_BUTTON, SERVO_MOTOR_CONTROL, DC_MOTOR_CONTROL,
STEPPER_MOTOR_CONTROL} MOTOR_BUTTON_INDEX_T;

As I want to use the master button index in one master struct for function buttons:

// function_button
struct function_button{
  uint16_t x;
  uint16_t y;
  uint16_t w;
  uint16_t h;
  uint16_t button_color;
  uint16_t text_color;
  char text[20];
  FUNCTION_BUTTON_INDEX_T button_number;
};

In case I want to do this:

function_button button1;

button1.button_number = SERVO_MOTOR_CONTROL;

Then of course that's an error.

I thought of using a void *FUNCTION_BUTTON_INDEX_T ; but that will require me to typecast every line after that.

Any suggestions ?

2

An enum is a type so you would end up with a kind of dual type in what you want to do if I got that right and There is no inheritance with enums

1 Like
3 
typedef enum : uint8_t {} FUNCTION_BUTTON_INDEX_T;

Please explain in English what this line of code does

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4

The best I could do is to typecast it, this one has no error. But I'm searching for a solution not to use typecast as much as I can.

    function_button b1;
    b1.button_number = (FUNCTION_BUTTON_INDEX_T)CURRENT_READING;
5

This may be relevant.

1 Like
6

I also think that I may not use enums, and instead go with defines and then use uint8_t.

7

OK, I think I solved the problem, I shouldn't use a master enum, and just use a variable inside the struct; like this:

This:

// function_button
struct function_button{
  uint16_t x;
  uint16_t y;
  uint16_t w;
  uint16_t h;
  uint16_t button_color;
  uint16_t text_color;
  char text[20];
  FUNCTION_BUTTON_INDEX_T button_number;
};

Should be this:

// function_button
struct function_button{
  uint16_t x;
  uint16_t y;
  uint16_t w;
  uint16_t h;
  uint16_t button_color;
  uint16_t text_color;
  char text[20];
  uint8_t button_number;
};

Then I can assign it like this:

function_button b_current = {40, 60, 150, 30, TFT_BLUE, TFT_WHITE, "CURRENT READING", CURRENT_READING};
function_button b_voltage = {40, 90, 150, 30, TFT_BLUE, TFT_WHITE, "VOLTAGE READING", VOLTAGE_READING};

And it compiled without errors.

8

I thought I cold use the name of the enum as a master type to hold the data for other enums.

9

You might want to consider inheritance and pure virtual functions

for example

class Button {
  protected:
    uint16_t x;
    uint16_t y;
    uint16_t w;
    uint16_t h;
    uint16_t button_color;
    uint16_t text_color;
    const char* text;
  public:
    Button(const char * lbl) : x(0), y(0), w(10), h(12), button_color(0), text_color(0xFFFF), text(lbl) {}
    virtual void action() = 0;  // Pure virtual
};

class ElectricalButton : public Button {
  public:
    ElectricalButton(const char * lbl) : Button(lbl) {}
    void action() {
      Serial.print("ElectricalButton action : ");
      Serial.println(text);
    }
};

class MotorButton  : public Button {
  public:
    MotorButton(const char * lbl) : Button(lbl) {}
    void action() {
      Serial.print("MotorButton action : ");
      Serial.println(text);
    }
};

MotorButton leftMotorButton("left engine");
MotorButton rightMotorButton("right engine");
ElectricalButton elecButton("power");

Button* myButtons[] = {&leftMotorButton, &rightMotorButton, &elecButton};

void setup() {
  Serial.begin(115200); Serial.println();
  for (auto && b : myButtons) b->action();
}

void loop() {}

Serial Monitor (@ 115200 bauds) will show

MotorButton action : left engine
MotorButton action : right engine
ElectricalButton action : power

➜ every Button has an action function and its behavior depends on the subclass but yet everything was stored in an array of pointers which types are from the base class.

1 Like
10

OK, thank you so much for this wonderful piece of code. This is completely different that my simple coding.

I stopped at the pure virtual functions before months and didn't come back to carry on that topic, but this should really put a good application advantage in my project :slight_smile:

11

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