Template singleton base class in shared object

Question

I\'m currently porting my project from Windows to Linux.

The project consists of a \'main\' shared library, several plugins (also shared libraries) and a launcher ap

Answer 1

IMHO the closest thing you can get that suffices your requirements is something using the following pattern:

#include <iostream>

template<class Derived>
class Singleton {
public:
    static Derived& instance() {
        static Derived theInstance;
        return theInstance;
    }

protected:
    Singleton() {}

private:
    Singleton(const Singleton<Derived>&);
    Singleton<Derived>& operator=(const Singleton<Derived>&);
};

---

class ASingleton : public Singleton<ASingleton> {
public:
    void foo() { std::cout << "foo() called ..." << std::endl; }
};

---

int main() {
    ASingleton& a = ASingleton::instance();
    a.foo();
    return 0;
}

Whatever you want to be accessible through an interface might be injected using multiple inheritance. Though the benefit of using a Singleton<Derived> base class is a bit questionable, it just provides that narrow instance() implementation.