Tuples

[BCS]

Reply to dsimcha,

> I've been thinking a little about the idea of returning tuples from
> functions, w.r.t. Bugzilla 2628
> (http://d.puremagic.com/issues/show_bug.cgi?id=2628).   Would it be
> feasible to solve this by making struct[index] for any struct w/o an
> opIndex overload equivalent to struct.tupleof[index]?  This would be
> trivial syntactic sugar, but would allow user-defined tuples in Phobos
> to look like a builtin tuple, be returned from functions, etc., while
> changing very little under the hood.   Furthermore, for functions that
> take a tuple, we could allow structs to be implicitly cast to tuples,
> e.g.:
> 
> struct Foo {
> uint u;
> float f;
> }
> void doStuff(uint myInt, float myFloat) {}
> 
> Foo foo;
> doStuff(foo);  // Implicitly casts to foo.tupleof, works.

I like the first part some (but not without reservations). As for the second 
bit... I don't like it. It would make overload resolution to tricky, if not 
at the compiler level than at the eyeball level.