C89-DP: Singleton

This one is gonna be short since there realy isn't much to it.

Example

typedef struct Foo Foo;

struct Foo
{
    int x;
};

Foo* Foo_getInstance()
{
    static Foo instance = { 0 };
    return &instance;
}

Only thing I need to note is that it's safe to take the reference of instance since it's stored in the static register. Besides that, the rest of the program works as expected. I could've instead opted for using extern, but I think this looks a little cleaner as I only expose what I want to expose.

Usage

Foo* foo = Foo_getInstance();

Conclusion

It absolutely can be done, in many ways even.