implementing default opCmp

[Steven Schveighoffer via Digitalmars-d-learn]

I have a struct like this:

struct S
{
   int x;
   int y;
}
and I want a default comparison. The problem is, that comparison doesn't 
have a default, and requires I implement opCmp. While this is useful for 
the compiler, there's no default I know of that is an easy one-liner.

The truth is, I'm not entirely caring what order these things come out 
in. I just want them to be defined as having an order given that all the 
members have a defined order. My expectation is that a default opCmp 
would look like:

int opCmp(S other)
{
   if(x == other.x)
   {
       if(y == other.y) return 0;
       return y < other.y ? -1 : 1;
   }
   return x < other.x ? -1 : 1;
}

But really, as long as there is something to do this easily I don't care 
what the ordering turns out to be.

I can do equality like:

return this.tupleof == other.tupleof;

I can do assignment like:

this.tupleof = other.tupleof;

How do I do something really simple for opCmp? I tried this it didn't work:

return this == other ? 0 :
    this.tupleof < other.tupleof ? -1 : 1;

-Steve