Why does std.container.array does not work with foraech( i, a; array ) {} ?

[ParticlePeter via Digitalmars-d-learn]

On Sunday, 29 May 2016 at 09:07:07 UTC, Jonathan M Davis wrote:
> On Sunday, May 29, 2016 07:14:12 ParticlePeter via 
> Digitalmars-d-learn wrote:
>> Which of the op(Index) operators is responsible for enabling 
>> this
>> kind of syntax?
>> Would it be possible to get it work with UFCS or would I have 
>> to
>> wrap the array?
>
> std.container.array.Array works with foreach via ranges.
>
> foreach(e; myContainer)
> {
> }
>
> gets lowered to
>
> foreach(e; myContainer[])
> {
> }
>
> which in turn gets lowered to something like
>
> for(auto r = myContainer[]; !r.empty; r.popFront())
> {
>     auto e = r.front;
> }
>
> Ranges do not support indices with foreach, and that's why 
> you're not able to get the index with foreach and Array. 
> However, if you use std.range.lockstep, you can wrap a range to 
> get indices with foreach. e.g.
>
> foreach(i, e; lockstep(myContainer[]))
> {
> }
>
> http://dlang.org/phobos/std_range.html#.lockstep
>
> - Jonathan M Davis


Thanks, due to your answer I found a way which is even better for 
me. I pimped the Array containers with some UFCS functions 
anyway, one of them returns the array data as a slice and this 
works nicely with that foreach variant as well

auto data( T )( Array!T array )  {
     if( array.length == 0 ) return null;
     return (&array.front())[ 0..array.length ];
}

// this works now
foreach( i, a; someArrayContainer.data ) { ... }

- PP