Event dispatch in C++ (Observer) for Sima. Kole asked for Threading bits.

gistfile1.txt

#include <stdio.h>
#include <Windows.h>
#include <process.h>


class IncrementInterface {
public: 
	virtual int increment(int amount) = 0;
};


class SimpleClass : public IncrementInterface 
{
public:
	int _value;
	int _id;

	SimpleClass(int initial_value, int id) : _value(initial_value), _id(id) {}

	// A method yielding result depending on internal state
	int increment(int amount) {
		_value += amount;
		printf(" increment event received id=%d val=%d \n", _id, _value);
		return _value;
	}

	typedef int (SimpleClass:: * IncrementMethodType) (int initial_value);
};


#include <deque>


struct Params {
	Calculator * _our_calc;
};

///
///
/// Threading used for events
///
///
class Calculator {
public:
	//
	// Events logic:
	// 
	std::deque<IncrementInterface *> _registered;
	void register_for_event(IncrementInterface * subject) {
		_registered.push_back(subject);
	}
	void incremented_event(int amount) {
		for (std::deque<IncrementInterface *>::iterator it = _registered.begin(); it!=_registered.end(); ++it) {
			(*it)->increment(amount);
		}
	}

	//
	// Threading logic:
	//
	uintptr_t _thread;

	Calculator() : _thread(0) {}

	void start() {
		Params * params = new Params;
		params->_our_calc = this;
		_thread = _beginthread(__run_in_thread, 60000, params);
	}

	static void __run_in_thread(void * a) {
		Params * p = (Params *) a;
		p->_our_calc->run();
		delete p;
	}

	// invoking events
	void run() {
		incremented_event(3);
		incremented_event(4);
		incremented_event(5);
	}

	void wait() {
		DWORD result = WaitForSingleObject( (HANDLE) _thread, INFINITE );
	}
};

int main() {

	SimpleClass obj(7, 1), obj2(5, 2);

	//
	// Using method pointers - dirty
	//
	int (SimpleClass:: * inc_pointer)(int) = &SimpleClass::increment;
	SimpleClass * _this = &obj;

	// call inc_pointer with this set to _this
	printf(" result: %d \n", (*_this.*inc_pointer)(3));
	printf(" result: %d \n", (_this->*inc_pointer)(4));
	printf(" result: %d \n", (*_this.*inc_pointer)(5));

	Calculator calc;
	calc.register_for_event(&obj);
	calc.register_for_event(&obj2);
	calc.start();
	calc.wait();

	return 0;
}