Repost: make foreach(i, a; range) "just work"

[Jesse Phillips]

On Friday, 21 February 2014 at 16:41:00 UTC, Regan Heath wrote:
> and make this possible too:
>
> 	foreach([index, ]value; range) { }

I understand the user interface is simple, but you created 3 
statements about how it could be achieved and work/not work with 
the existing setup. Each have their positives and negatives, it 
would not make sense to "just choose one" and hope it all works 
out.

>> if AA is changed to a double[string], then your value loop 
>> iterates on keys and your key loop iterates on values.
>
> No, I was actually suggesting a change here, the compiler would 
> use type matching not ordering to assign the variables.  So 
> because 'v' is a string, it is bound to the value not the key.

And string is the key, double[string] is not the same as 
string[double].

Also string[string], ambiguous yet common.

There are many things to consider when adding a feature, it is 
not good to ignore what can go wrong.

> Thanks!  Ok, so how is this working?  ahh, ok I think I get it.
>  enumerate returns a range, whose values are Tuples of 
> index/value where value is also a tuple so is flattened, and 
> then the whole lot is flattened into the foreach.

Sounds like you understand it, seams foreach will flatten all 
tuples.

> I don't think this affects what I actually want to change, we 
> can have:
>
> 	foreach(index, value; range) { }
>
> and still flatten tuples into value, you would simply have to 
> provide one extra variable to get an index.
>
> Make sense?

Yes, but I'm saying we don't need it because

	foreach(index, value; range.enumerate) { }

is good enough. Not perfect, but good enough.