Array of a type with different types inside

Question

I'm creating an Array of a Class Type (Button), and I want to have a subclass of it called ButtonMb inside the array Button Is that possible? I tried to have two different constructors and use only one Class, but since number of parameters are the same, I couln't reach anywhere.

Here is my code: for simplicity I only included header code for class declaration

typedef void (*Callback)(void);
typedef int (*CallbackInt)(void);

class Button {
  public:
    OneButton _pin;

    Button(uint8_t pin, Callback click=NULL, Callback longCl=NULL, Callback dblCl=NULL);
  
    void loop();
};

class ButtonMb : public Button {
  public:
    CallbackInt _pinState;

    ButtonMb(CallbackInt pinState, Callback click=NULL, Callback longCl=NULL, Callback dblCl=NULL);
    
    void loop();
};

Button buttons[2] = {
  Button(14),
  ButtonMb([](){return slaves[0].getState("A15");)
};

Any help?

NOTE: I'm using Arduino, so code can be limited.

Nope, sorry, arrays in C++ don't work this way.

Sam Varshavchik
– Sam Varshavchik

2021-01-27 23:08:21 +00:00
Commented Jan 27, 2021 at 23:08 — Sam Varshavchik
– Sam Varshavchik, Commented Jan 27, 2021 at 23:08

ziemowit141 · Accepted Answer · 2021-01-27 23:03:52Z

1

Instead of using array of objects, you can create array of pointers. Pointers of base class can point to derived classes, so you can have pointers to objects of different types in one array.

answered Jan 27, 2021 at 23:03

ziemowit141

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3 Comments

Ricardo Reis Over a year ago

like this? Button* buttons[2]={Button(14), ButtonMb(...)};

ziemowit141 Over a year ago

Close, it would be better if you first allocated those buttons on heap, now you tried to insert objects instead of pointers pointing to the objects. Button* b_ptr = new Button(14); Button* mb_ptr = new ButtonMb(...); Button* buttons[2]={b_ptr, mb_ptr);

user4581301 Over a year ago

There may be no need for dynamic allocation. For example, Button button(14); ButtonMb buttonmb(...); Button* buttons[]={&button, &buttonmb};. If you find yourself needing dynamic allocation, consider using a smart pointer to manage the allocation: std::unique_ptr<Button> buttons[]={std::make_unique<Button>(14), std::make_unique<ButtonMb>(...)};. documentation for std::unique_ptr and documentation for std::make_unique.

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