repos/Callback_20/Callback_20.cpp

// Callback_19.cpp : Diese Datei enthält die Funktion "main". Hier beginnt und endet die Ausführung des Programms.
//

#include <iostream>
/**
 * Example code for:
 *   - callback storage with std::vector
 *   - use of std::function
 *   - use of std::bind
 *   - use of lambda function as callback
 */

#include <cstdint>
#include <cstdio>
#include <functional>
#include <vector>

 /**
  * Basic std::function callback example. Templated on a function signature
  * that takes in a uint32_t and returns void.
  */

struct myData {
	uint8_t myAge = 55;
	const char* pchar = "myData struct";
	enum en_sex { MALE, FEMALE, DIVERS } sex = MALE;
};

myData mydata = { 25, "myData struct", myData::MALE };



typedef std::function<void(myData)> cb_t;

/**
 * Alternative storage implementation.  Perhaps you want to store
 * callbacks for different event types?
 */
enum my_events_t
{
	VIDEO_STOP = 0,
	VIDEO_START,
	VIDEO_PAUS,
	EVENT_MAX
};

struct cb_event_t
{
	std::function<void(myData)> cb;
	my_events_t event;
};


/**
 * Event based example.  Constructed with a uint32_t.
 * Callbacks are passed this uint32_t.
 * Callbacks are only invoked when their event type matches the
 * occuring event.
 */
class EventDriver
{
public:
	// EventDriver(myData& val) : val_(val), callbacks_()
	EventDriver() {};

	// Register a callback.
	void register_callback(const cb_t& cb, const my_events_t event)
	{
		// add callback to end of callback list
		callbacks_.push_back({ cb, event });
	}

	/// Call all the registered callbacks.
	void callback(myData& val, my_events_t event) const
	{
		// iterate through callback list and call each one
		for (const auto& cb : callbacks_)
		{
			if (cb.event == event)
			{
				cb.cb(val);
			}
		}
	}

private:
	/// Integer to pass to callbacks.
	// myData *val_ = nullptr ;
	/// List of callback functions.
	std::vector<cb_event_t> callbacks_;
};


/***********************************************************************************************************************
 * Dummy Client #1
 * Uses a static method for a callback.
 */
class Client1
{
public:
	static void func(myData v)
	{
		printf("static member callback: %d\n", v.myAge);
	}
};

/***********************************************************************************************************************
 * Dummy Client #2
 * Uses an instance method as a callback
 */
class Client2
{
public:
	void func(myData v) const
	{
		printf("instance member callback: %d\n", v.myAge);
	}
};

/***********************************************************************************************************************
 *    Callback on a c function
 */
extern "C"
{
	static void c_client_callback(myData v)
	{
		printf("C function callback: %d\n", v.myAge);
	}
}

/***********************************************************************************************************************
 *    Callback on a c function
 */
class cButton : public EventDriver {
public: 
	/**
     * Examples using the basic driver
     * This is constructed with a specific value
     * Each callback receives this value
     */
	Client2 c2;

	void init() {
	
	    // register a lambda function as a callback
		register_callback(
			[](myData mydata) {
				printf("lambda callback: %d\n", mydata.myAge);
			},
			VIDEO_START);

		// register a lambda function as a callback
		register_callback(
			[](myData mydata) {
				printf("lambda callback: %d\n", mydata.myAge);
			},
			VIDEO_STOP);

		// register client2 cb using std::bind
		register_callback(std::bind(&Client2::func, &c2, std::placeholders::_1), VIDEO_START);

		// register a static class method as a callback
		register_callback(&Client1::func, VIDEO_STOP);

		// register a C function pointer as a callback
		register_callback(&c_client_callback, VIDEO_PAUS);

	};
	void run() {	
		// call all the registered callbacks
		printf("-------   VIDEO_START -------\n");
		mydata.myAge = 15;
		callback(mydata, VIDEO_START);
		printf("-------   VIDEO_STOP -------\n");
		mydata.myAge = 25;
		callback(mydata, VIDEO_STOP);
		printf("-------   VIDEO_PAUSE -------\n");
		mydata.myAge = 35;
		callback(mydata, VIDEO_PAUS);
	};

	void readData() {};
};

/***********************************************************************************************************************
 *    Callback on a c function
 */
int main()
{
	/**
	 * Examples using the Event Driver.
	 * Note that some callbacks will not be called -
	 * their event type is different!
	 */
	cButton btn;



	printf("Beginning of examples using the EventDriver\n");

	btn.init(); 
	btn.run();

	printf("\nEnd of examples using the EventDriver\n");

	return 0;
}