Revision b3bd191c-1139-45e6-bcdb-16af10bc1b06 - Arduino Stack Exchange

I am trying to pass a class internal function as a callback function within the class. The error behavior is similar to [this problem][1]. Whatsoever, I was unable to construct working code based on that question's answer. 

I try to pass over a callback function from within the class,in order to create a finite state machine, inspired by the examples I found on adafruit regarding multithreading. The idea is, that each state can call his successor. The class itself then represents the state machine and I just will call its update function.

While the following code does not resemble this utility, it resembles the problem in a minimal example (based on [this larger codepiece][2]):

 class MyClass
 {
 const byte theAnswer = 42;
 void (*myCallback)();
 
 void setCallback(void (*callback)())
 {
 myCallback = callback;
 }
 
 public:
 
 void print_info()
 {
 Serial.println(theAnswer);
 }
 
 void call()
 {
 myCallback();
 }
 
 MyClass()
 {
 setCallback(&MyClass::print_info);
 }
 };
 
 
 MyClass AClassOfItsOwn();
 
 void setup() 
 {
 Serial.begin(9600);
 while (! Serial); // Wait until Serial is ready
 }
 
 void loop() 
 {
 AClassOfItsOwn.call();
 return;
 }

I get the following error code returned:

> ...testscript.ino: In constructor 'MyClass::MyClass()':
> 
> testscript:25: error: no matching function for call to
> 'MyClass::setCallback(void (MyClass::*)())'
> 
> setCallback(&MyClass::print_info);
> 
> ^
> 
> ...\testscript.ino:25:41:
> note: candidate is:
> 
> ...\testscript.ino:6:12:
> note: void MyClass::setCallback(void (*)())
> 
> void setCallback(void (*callback)())
> 
> ^
> 
> ...\testscript.ino:6:12:
> note: no known conversion for argument 1 from 'void (MyClass::*)()'
> to 'void (*)()'
> 
> ...\testscript.ino:
> In function 'void loop()':
> 
> testscript:40: error: request for member 'call' in 'AClassOfItsOwn',
> which is of non-class type 'MyClass()'
> 
> AClassOfItsOwn.call();
> 
> ^
> 
> exit status 1 no matching function for call to
> 'MyClass::setCallback(void (MyClass::*)())'


----------
**fun times with polymorphism**
this is what I tried till now. I also tried creating an instance of this wrapper within the actual class to hold the callback, but that did not work either. Sorry I am a bit cumbersome with C++, coming from another language and apparently bit off a bit more than I could chew... 


 class CallbackWrapper
 {
 void (*myCallback)();
 public:
 
 void call()
 {
 myCallback();
 }

 void setCallback(void (*callback)())
 {
 myCallback = callback;
 }
 };
 
 class MyClass : public CallbackWrapper
 {
 const byte theAnswer = 42;
 public:
 
 void print_info()
 {
 Serial.println(theAnswer);
 }
 
 MyClass()
 {
 CallbackWrapper::setCallback(&MyClass::print_info);
 }
 };

trying to store the callback function in a wrapping class (also not working, `'((MyClass*)this)->MyClass::CBW' does not have class type`)

 class CallbackWrapper
 {
 void (*myCallback)();
 public:
 
 void call()
 { myCallback(); }

 void setCallback(void (*callback)())
 { myCallback = callback; }
 };
 
 class MyClass 
 {
 const byte theAnswer = 42;
 CallbackWrapper CBW();
 public:
 void print_info() { Serial.println(theAnswer); }
 void call() { CBW.call(); }
 MyClass()
 { CBW.setCallback(&MyClass::print_info); }
 };

 [1]: http://arduino.stackexchange.com/questions/14480/pass-a-member-function-pointer-to-a-method-of-a-foreign-class-edb-lib
 [2]: https://learn.adafruit.com/multi-tasking-the-arduino-part-3/put-it-all-together-dot-dot-dot