How to make a singleton class BlackBerry 10

Question

Suppose we have to use a single object of a class throughout the lifetime of an application. In BlackBerry 10, is it possible to declare a global object, which can be used anywhere inside the program?

Answer 1

You could do that, but a better way may be to use a class designed to be a singleton:

Singleton.hpp

class Singleton {
private:
    Singleton();

public:
    virtual ~Singleton();
    static Singleton &instance();

    int getMemberField() { return m_memberField; }
    void setMemberField(int mf) { m_memberField = mf; }

private:
    static Singleton    *p_instance;

    int                 m_memberField;
};

Singleton.cpp

Singleton*    Singleton::p_instance = NULL;

Singleton::Singleton() {
    p_instance = this;
    m_memberField = 0;
}

Singleton::~Singleton() {
    p_instance = NULL;
}

Singleton&    Singleton::instance() {
    if (p_instance == NULL) {
        p_instance = new Singleton();
    }
    return *p_instance;
}

In application code

Singleton::instance().setMemberField(25);
Singleton::instance().getMemberField();

The real benifit of this is that the singleton looks after its own global pointer.