main.cpp

#include "singleton.h"
#include <QCoreApplication>

int main(int argc, char *argv[])
{
        QCoreApplication ca(argc, argv);
        Singleton::instance()->init();
        return 0;
}

singleton.cpp

#include "singleton.h"

Singleton::Singleton() : QObject(NULL)
{
}

template <typename T>
class MyGlobalStatic
{
public:
    T *pointer;
    inline MyGlobalStatic(T *p) : pointer(p) { }
    inline ~MyGlobalStatic() { pointer = 0; }
};

Singleton *Singleton::instance()
{
        static Singleton s;
        static MyGlobalStatic<Singleton> st(&s);
        return st.pointer;
}

Singleton::~Singleton()
{
}

void Singleton::init()
{
        Singleton *s = Singleton::instance();
        const QMetaObject *mo = s->metaObject();
        qDebug(mo->className());
}

singleton.h

#include <QObject>

class Singleton : public QObject
{
        Q_OBJECT

public:
        ~Singleton();

        static Singleton *instance();

        void init();

private:
        explicit Singleton();
};

test.pro

TEMPLATE = app
SOURCES += main.cpp singleton.cpp
HEADERS += singleton.h

QT = core