<unresolved overloaded function type>

Projects Programming
1

Hi,

I don't get the code below working (except with the wrapper function). I do not want to use the wrapper function because it kills the function callback idea. How can I write the code without writing the wrapper function? Hope you can help me, thx.

This is the code that gives the error:

#include <TimedAction.h>
#include <Time.h>
#include <TimeAlarms.h>

const unsigned long timeout10Sec = 10000; //10 sec.

TimedAction boilerTimeout = TimedAction(timeout10Sec, boilerPowerOff);

void boilerPowerOff(){
  //power off te boiler.
}

void setup(){
  setTime(8,29,0,1,1,10); // set time to 8:29:00am Jan 1 2010
  // create the alarms
  Alarm.alarmRepeat(8,30,0, boilerTimeout.reset);
}

void loop(){
  boilerTimeout.check();
}

I receive this error message:

error_example.cpp: In function 'void setup()':
error_example:19: error: no matching function for call to 'TimeAlarmsClass::alarmRepeat(int, int, int, <unresolved overloaded function type>)'
C:\Users\athome\Dropbox\Home automation\Arduino\arduino-0022\libraries\TimeAlarms/TimeAlarms.h:69: note: candidates are: AlarmID_t TimeAlarmsClass::alarmRepeat(time_t, void (*)())
C:\Users\athome\Dropbox\Home automation\Arduino\arduino-0022\libraries\TimeAlarms/TimeAlarms.h:70: note:                 AlarmID_t TimeAlarmsClass::alarmRepeat(int, int, int, void (*)())
C:\Users\athome\Dropbox\Home automation\Arduino\arduino-0022\libraries\TimeAlarms/TimeAlarms.h:71: note:                 AlarmID_t TimeAlarmsClass::alarmRepeat(timeDayOfWeek_t, int, int, int, void (*)())

This is the code with the wrapper function which works fine:

#include <TimedAction.h>
#include <Time.h>
#include <TimeAlarms.h>

const unsigned long timeout10Sec = 10000; //10 sec.

TimedAction boilerTimeout = TimedAction(timeout10Sec, boilerPowerOff);

void boilerPowerOff(){
  //power off te boiler.
}

void wrapper(){
  boilerTimeout.reset();
}

void setup(){
  setTime(8,29,0,1,1,10); // set time to 8:29:00am Jan 1 2010
  // create the alarms
  Alarm.alarmRepeat(8,30,0, wrapper);
}

void loop(){
  boilerTimeout.check();
}
2

I think a typecast will sort this out, case the boilerTimeout.reset to the right function type.

3

But what is the correct typecast? The callback is defined as a simple void.

void (*OnTick_t)()

I just don't get it right :(.

4

Unfortunately, the wrapper is the way to go. Your function boilerTimeout.reset() is a member function of an object - what is implied in an object is that there is a pointer to the object (called 'this') that is passed through. C++ hides the pointer in many cases from view, but that means that the actual function here is not

void boilersomething::reset()

but (very, very roughly)

void boilersomething::reset(void*thisPtr)

So you can see why the function fails, and why you need the wrapper. If the function was not an object class member function, or was static, you'd be fine.

5

Thx David, that is the problem :).

I found a very good in-depth explanation of the problem here: The Function Pointer Tutorials - Callbacks