Callbacks Made Easy with the Observer/Mediator Design Patterns
By Vladimir Batov, February 01, 2001
Good software works; great software evolves. Here's a variation on the Observer pattern that lets you update your code base with ease.
February 2001/Callbacks Made Easy with the Observer/Mediator Design Patterns/Listing 2
class Signal
{
public: ~Signal () {}
private: Signal () {}
public:
class Event {...};
template<class Subject, class Observer, class UserEvent>
static
void
connect(
Subject&, Observer&,
void (Observer::*)(const UserEvent&, Subject*));
template<class Subject, class Observer, class UserEvent>
static
void
connect(
Subject&, Observer&,
void (*)(const UserEvent&, Subject*, Observer*));
template<class Subject, class Observer, class UserEvent>
static
bool
disconnect(
Subject&, Observer&,
void (Observer::*)(const UserEvent&, Subject*));
template<class Subject, class Observer, class UserEvent>
static
bool
disconnect(
Subject&, Observer&,
void (*)(const UserEvent&, Subject*, Observer*));
template<class Subject, class UserEvent>
static
void
emit(Subject&, const UserEvent&);
private:
struct Callee {};
typedef void (Callee::*MemberCallback)
(const Event&, void*);
typedef void (*LonelyCallback)
(const Event&, void*, void*);
class Parcel {...};
typedef list<Parcel> List;
typedef map<const void*, List> Map;
Map _map;
void _emit (void*, const Event&);
void _connect (const void*, const Parcel&);
bool _disconnect (const void*, const Parcel&);
static Signal& _signals ();
};
— End of Listing —
