type of if statement used for operator overloading?

[Jeremy DeHaan]

I've seen operator overloading done 3 different ways. In the 
examples I provide they all compile and work as far as I can 
tell. Is there any major difference between using a static if vs 
a regular if, or any situation that one would be better than the 
other?


struct Something1
{
    Something1 opUnary(string s)()
    {
        if (s == "-")
        {
           return stuff;
        }
    }

}

struct Something2
{
    Something2 opUnary(string s)()
    {
        static if (s == "-")
        {
           return stuff;
        }
    }

}

Also, I realize that if I wanted to overload just a single 
operator and that was all, I could do:

struct Something3
{
    Something3 opUnary(string s)()
       if (s == "-")
    {

        return stuff;

    }

}

But I am more curious about the first two.

Thanks as usual guys!
Jeremy