Don't understand this piece of code

Projects Programming
1

Please have a look at the following piece of code. I'm trying to get my head around how this works, but I'm not very successful at that.
The biggest question mark for me is that it looks to me like a function (paramAction) is defined twice, but called with a different number of parameters at different places.
Looks like some recursive calling of functions is going on here, but I'm not sure...

Can someone please enlighten me ?

template<typename T> void paramAction(uint8_t action, volatile T& value, uint8_t menuid, 
    const char* label, void (*display)(const char* enumArray[], int32_t value, int32_t _min),
    const char* enumArray[], int32_t _min, int32_t _max, void (*trigger)(int) ) {

  switch(action) {
    case UPDATE:
    case UPDATE_MENU: {
      // do stuff
      break;
    }
    default:
      actionCommon(action, (uint16_t *)&value, sizeof(value)/2);
      break;
  }
}

void paramAction(uint8_t action, uint8_t id = ALL) {
  if ((action == SAVE) || (action == LOAD)) {
    // do other stuff
  }

  switch (id) {
    case ALL:     for(id = 1; id != N_ALL_PARAMS+1; id++) paramAction(action, id);
    case VERS:    paramAction(action,eeprom_version,0,NULL,displayNum,NULL,0,0,triggerNoop);break;
  }
}

void setup() {
  paramAction(LOAD,VERS);
  // do something
  paramAction(LOAD);
}
2

That is called function overloading. The compiler decides which of the different definitions to use, depending on the parameters used by the calling program.

3

Exactly, it is called function overloading.
In this case one uses several default parameters and the other allows custom settings.

4

Wow, that's quick. I was still editing the question for more clarity...
However, I'm afraid I still do not quite understand this.

How does this work runtime ?
Has the compiler created code in the executable that represents two versions of paramAction ? One piece of code that calls paramAction with one (or two) parameters, and one piece of code that calls paramAction with nine parameters ?

5

Yes, but both aren't necessarily included in the final machine code, unless your program calls both versions with appropriate parameters.

6

Thanks guys,

Yes, the code does use both forms of paramAction.

BTW, respect. I have never had answers this quickly on whatever forum I've posted on. I believe I understand how this works now.

Thanks again !