BidirectionalRange switching direction

[Tofu Ninja via Digitalmars-d-learn]

On Wednesday, 23 September 2015 at 03:26:29 UTC, John Colvin 
wrote:
> On Wednesday, 23 September 2015 at 02:10:22 UTC, Tofu Ninja 
> wrote:
>> Trying to implement a bi directional range and it is slightly 
>> unclear what the semantics are supposed to be and just wanted 
>> some clarification.
>>
>> Are bidirectional ranges supposed to be able to support 
>> switching direction mid iteration? Like if I do popFront 
>> popFront popBack should that be equal to just a single 
>> popFront? Or once you start on a direction should switching be 
>> considered an error? Or is popFront and popBack supposed to 
>> consume from both ends of the range and the range is empty 
>> when they meet?
>>
>> -tofu
>
> The last one. E.g. for arrays (except narrow strings... ugh)
>
> auto popFront(T)(ref T[] a)
> {
>     a = a[1 .. $];
> }
>
> auto popBack(T)(ref T[] a)
> {
>     a = a[0 .. $-1];
> }

Ok cool, that's what I ended up doing.