IObserver

[LiuYinChina]

interface IObservable;

interface IObserver
{
virtual void update(IObservable *pObservable) = 0;
virtual void update(IObservable *pObservable) const = 0;
};

interface IObservable
{
typedef std::set<IObserver *> container_type;
typedef container_type::iterator iterator;
typedef container_type::const_iterator const_iterator;

virtual void notify() {
const_iterator it;
for (it = m_setObserver.begin(); it != m_setObserver.end(); ++it) {
(*it)->update(this);
}
}

void addObserver(IObserver *pObserver) { m_setObserver.insert(pObserver); }
void removeObserver(IObserver *pObserver) { m_setObserver.erase(pObserver); }

private:
container_type m_setObserver;
};

class A : public IObservable
{
public:
A () : m_int (0) {}

void setInt(int _int) {
if (_int == m_int) {
return;
}

m_int = _int;
notify();
}

int getInt() {
return m_int;
}

private:
int m_int;
};

class B : public IObserver
{
public:
virtual void update(IObservable *pObservable) {
A *pA = 0;
if (!Dynamic_Cast(pA, pObservable)) {
return;
}

cout << pA->getInt() << endl;
}

virtual void update(IObservable *pObservable) const {
A *pA = 0;
if (!Dynamic_Cast(pA, pObservable)) {
return;
}

cout << pA->getInt() << endl;
}
};

void _tmain()
{
A a;
B b1;
B b2;

a.addObserver(&b1);
a.addObserver(&b2);

a.setInt(1);
}

[SeekTruth]

有些牵强了，远不如使用委托来得优雅