Pass extra parameter into callback function

[dautushenka]

Hi everyone, I need help with feature that pass additional parameter into callback function

/* Library code */
typedef void (*cb)(int x);

bool libraryFunc(int param, cb cbFunc) {
 // doing something and then call cb
}
/* end Library code */

void callback(int x, int extraData) {

}

// Here I need wrap callback function to add extraData value
 libraryFunc(3, callback)

What I was trying to do:

1. using std::bind (it looks like not available for arduino (()
2. Using lambda function, it was hard to cast lamda to function pointer type especially if these is captured variables

Might be somebody has a other idea how to do it.
The library code can not be changed

[gfvalvo]

@dautushenka

• using std::bind (it looks like not available for arduino (()
• Using lambda function, it was hard to cast lamda to function pointer type especially if these is captured variables

Which Arduino board? You're correct that std::bind and std::function are not available for AVR-based boards (Uno, Mega, etc). However, they are available for ARM and ESP32/8266 - based boards.

[jfjlaros]

@dautushenka

Might be somebody has a other ideas how to do it.

If extraData is known at compile time, you could use a template. E.g.,

bool libraryFunc(int param, cb cbFunc) {
  cbFunc(param);
  return false;
}

template <int extraData> void callback(int x) {
  Serial.println(x * extraData);
}

void setup() {
  Serial.begin(9600);
  libraryFunc(3, callback<10>);  // Prints "30";
}

[dautushenka]

Arduino Nano currently, got it, thanks