Template Method - Laurent Henocque

Double Checked Locking
class Singleton {
public:
static Singleton * instance();
private:
static Singleton * self;
static SEMAPHORE key;
}
Singleton *Singleton::instance() {
if (self == 0) {
if ( lock(key) >= 0 ) {
if (self == 0 ); //double-check!
self = new Singleton;
unlock (key);
} } }