possible improvement to if statements?

[Steven Schveighoffer]

We have this pattern in D, which is pretty nice:

if(auto p = x in y)
{
    // use p which is a pointer
}

But pointers can be difficult to use -- you sometimes have to 
dereference them to use them, and you can't create a reference variable 
in-line.

What about something like:

if(ref p = ptrExpression)
{
}

The expression would be a pointer expression. p would be bound to the 
pointer target, but the if statement is on the pointer itself. That is, 
you get inside only if p is referring to something not null.

I realize this is not going to fly, because there are too many holes. 
But I've wished for something like this a few times.

You can ALMOST get there with a kooky foreach helper (foreach is one of 
the few places where a ref local can be added into a function scope):

struct RefOf(T)
{
     T* ptr;
     ref T front() { return *ptr; }
     bool empty() { return ptr is null; }
     void popFront() { ptr = null; }
}

RefOf!T refof(T)(T * ptr) { return RefOf!T(ptr); }

foreach(ref r; (x in y).refof)
{
}

but you can't do `else` with it. You can wrap it in an if like this:

if(auto p = x in y) foreach(ref r; p.refof) {
    // ugh...
}
else
{
}

Does anyone have a workable way this kind of thing could be added to D?

-Steve