How to convert a singleton in c# to c++?

Question

I have this c# code:

class Animacion
{

    private static Animacion instancia;
    public static Animacion Instance
    {
        get
        {
            if (instancia == null)
            {
                instancia = new Animacion();
            }
            return instancia;
        }
    }

I want to convert that code to c++, I tryed to use a code converter from tangible software solutions and I got this:

//.h file code:

class Animacion
{

    private:
        static Animacion *instancia;
    public:
        static Animacion *getInstance() const;
};

//.cpp file code:

Animacion *Animacion::getInstance() const
{
    if (instancia == nullptr)
    {
        instancia = new Animacion();
    }
    return instancia;
}

When I use the code generated from the converter I get errors like:

error: C2272: 'getInstance' : modifiers not allowed on static member functions

can anyone help me?

https://stackoverflow.com/questions/1008019/c-singleton-design-pattern/1008289#1008289 — Galik, Sep 13 '15 at 20:03

πάντα ῥεῖ · Accepted Answer · 2015-09-13T20:23:22.760

static Animacion *getInstance() const; get rid of the const. There's no point making a static class member function const in c++, hence the compiler error.

Also the established idiom for singletons in c++ looks rather like:

class Animacion {

private:
    Animacion() {}
    Animacion(const Animacion&) = delete;
    Animacion& operator=(const Animacion&) = delete;
public:
    static Animacion& getInstance() {
        static Animacion theInstance;
        return theInstance;
    }
};

Further you should note, that Singleton is a really questionable design pattern, and you likely could live without it, in preference of an injected interface for the clients. That would help in decoupling implementation, from usage.

How to convert a singleton in c# to c++?

1 Answers1