Question

I have a singleton class that implements two other abstract classes.

My monkey::getMonkey fails because of thisMonkey = new monkey() returns “object of abstract class type “monkey” is not allowed”. I know you cannot instantiate abstract classes, but my monkey implements two abstract classes (meaning it is not abstract.. right?)

What is a solution to this?

class monkey : public animal,
               public npc {
public:
    ~monkey();
    static monkey* getMonkey();

private:
    monkey();
    static monkey* thisMonkey;

}




monkey::monkey() {};

monkey::~monkey() {};

/* .. implements the virtual methods of animal and npc ... */

monkey::getMonkey() {
    if (!thisMonkey)
        thisMonkey = new monkey();
    return thisMonkey;
}

Answer 1

You don’t show enough to say exactly, but a priori, your class monkey
doesn’t implement all of the pure virtual functions in the base class. A class which has pure virtual functions which haven’t been overridden is abstract.