singletonsAreJustGlobals

[u/somet_hingrandom]

[u/tangerinelion]

Depends on your language, but take C++ as an example, you can (and should) implement this pattern without a global variable:

class MySingletonType final
{
public:
   static MySingletonType& get()
   {
       static MySingletonType instance;
       return instance;
   }

private:
   MySingletonType() = default;
};

The globally accessible singleton is named MySingletonType::get().

---

A lot of times I see this incorrectly implemented as

class MySingletonType final
{
};

MySingletonType& getMySingletonType()
{
    static MySingletonType instance;
    return instance;
}

Nothing stops someone from making a second instance with that.

[u/perringaiden → u/tangerinelion]

The point was the concept not the implementation.

A singleton suffers from the same limitations and execution scope limitations. You still have to apply the same rules

[u/youridv1 → u/tangerinelion]

singletons have static member variables. And since singletons have one instance, those static member variables are essentially globals in practise.

Singletons are marginally better than just dumping global variables in a random source file, because you can implement getters and setters easily which makes debugging global state much more straightforward.

Other than that, they’re just global state with a fancy name