getNext

[Ellery Newcomer]

On 07/12/2010 10:48 PM, Andrei Alexandrescu wrote:
> I think I figured out a comfortable and all-encompassing means to define
> a simplified interface for an input range.
>
> Currently input ranges need to define empty, front, and popFront. That
> works but it's a bit heavy for simple input ranges. We've been
> discussing simplified interfaces in this group but couldn't find one
> that satisfied all use cases.
>
> Consider this:
>
> T* getNext(R, T)(ref R range, ref T item);
>
> Semantics: if the range wants to expose addresses of its elements, it
> returns a pointer to the current element and also advances to the next
> element. Otherwise (i.e. the range does not have or does not want to
> expose addresses of its elements), the range fills "item" with the
> current value, again moves on to the next value, and returns &item.
>
> In all cases, when there are no more elements in the range, getNext
> returns null.

let's see here

Range AhmAStream;

ubyte[] buf = new ubyte[4];
ubyte[]* ruf = AhmAStream.getNext(buf);
assert(ruf && ruf.length == 4);
int i = * (cast(int*) ruf.ptr)
buf = new ubyte[i];
ruf = AhmAStream.getNext(buf);
assert(ruf && ruf.length == i);

Something like this could work within this interface, couldn't it?

Think you might be on to something

>
> getNext is easy to define for e.g. arrays and files. How does it sound?
> Does it bring significant simplification?
>
>
> Andrei