How is `auto` and not `alias` appropriate for alias sequences?

[Shriramana Sharma via Digitalmars-d]

Another twist to this is that the tuple created by .tupleof doesn't really 
seem to be a new object of type Tuple!() but rather a "view" of sorts onto 
the original object itself in the form of a tuple, else the example provided 
at http://dlang.org/spec/class.html i.e.:

class Foo { int x; long y; }
void test(Foo foo)
{
    foo.tupleof[0] = 1; // set foo.x to 1
    foo.tupleof[1] = 2; // set foo.y to 2
    foreach (x; foo.tupleof)
        write(x);       // prints 12
}

wouldn't be able to set values to the original class instance via whatever 
.tupleof generates.

So the exact nature of the object produced by .tupleof is still a mystery to 
me. Would be good if someone threw more light on it.

Also: what is the use of presenting the members of a struct/class as a 
tuple? Is it iteration?

-- 
Shriramana Sharma, Penguin #395953