A Discussion of Tuple Syntax

[Tyler Jameson Little]

On Tuesday, 20 August 2013 at 21:25:11 UTC, Andrei Alexandrescu 
wrote:
> On 8/20/13 1:24 PM, Dicebot wrote:
>>> That would be problematic to say the least. (There have been 
>>> a few
>>> discussions in this group; I've come to think auto expansion 
>>> is fail.)
>>
>> :O it is awesome!
>
> "Spawn of Satan" would be a tad more appropriate.

+1

I can stand explicit expansion though, like Go's variadic 
argument ellipses syntax: 
http://golang.org/doc/effective_go.html#append

OT: I'm not really a fan of D's variadic function syntax. I'd 
prefer it to be explicit:

     int sum(int[] ar ...) {
     }
     int[3] foo = [4, 5, 6];
     sum(foo...);
     sum(3, 4, foo...); // on my wish list...

>> Stuff like foo(myStructInstance.tupleof) is very
>> powerful tool for generic interfaces.
>
> One problem with automatic expansion is that now there's a 
> whole new kind - a single expression that doesn't quite have 
> one value and one type, but instead is an explosion of other 
> expressions.
>
> snip...
>
> Alternatively, we could do what Go does and prevent all packing 
> altogether (if I understand what Go does correctly). That is, 
> if a function returns a tuple you can't even keep that tuple 
> together unless you use some handcrafted solution. In that 
> case, before long there will be some "Pack" structure and some 
> pack helper function, viz. the converse of .expand.

+1

I've been itching for multiple returns in D for a long time, and 
this seems like a nice way to add it in. I think I'd prefer to 
use tuple syntax instead though, just so there's less magic:

     (int, int) doStuff() {
         return (1, 2);
     }

     // syntax error
     auto a, b = doStuff();
     // ok
     auto (a, b) = doStuff();

> Clearly both packing and unpacking tuples are necessary.
>
> snip...
>
> Andrei

OT: is the only thing stopping us from using the nice (x,y) 
syntax for tuples the comma operator? If so, can we take that 
mis-feature behind the woodshed and shoot it? I sincerely hope 
nobody is relying on it...