A devil self reference

[Alex]

Hi all.
Finally, I arrived at something like this:

´´´
void main()
{
	S!(sarr)[] sarr;
}

struct S(alias Reference)
{
	size_t id()
	in
	{
		// not static assert, only because a pointer is never known in 
advance
		assert(Reference.ptr <= &this);
	}
	do
	{
		return &this - Reference.ptr;
	}
}
´´´

Of course, this does not compile, because I try to use an 
identifier before I defined it.

However, the reason I dare to ask is, that all the stuff with the 
weird self reference is compile time known.

So, is there a possibility to define something like the thing 
above?