Iterators in structs

[Paul Backus]

On Thursday, 25 June 2020 at 18:47:42 UTC, repr-man wrote:
> struct ChunksOf(R)
> {
>     Chunks!R iter;
>
>     this(R r, size_t width)
>     {
>         this.iter = r.chunks(width);
>         assert(is(typeof(iter) == Chunks!R));
>     }
> }
>
> This works, only if I change the declaration of x in main() to:
>
>     auto x = ChunksOf!(chain(a[], b[]))(chain(a[], b[]), 2);
>
> This requires me to pass the iterator as a template parameter 
> and a regular parameter.  Since this is a bit redundant, and I 
> wanted to know if there was a better way to do it.
>
> Thanks for the help!

The usual solution is to create a helper function:

ChunksOf!R chunksOf(R)(R r, size_t width)
{
     return ChunksOf!R(r, width);
}

The compiler can infer template arguments for function calls, so 
you can call it like this:

auto x = chunksOf(chain(a[], b[]), 2);