byChunk odd behavior?

[cym13 via Digitalmars-d-learn]

On Wednesday, 23 March 2016 at 03:17:05 UTC, Hanh wrote:
> Thanks for your help everyone.
>
> I agree that the issue is due to the misusage of an InputRange 
> but what is the semantics of 'take' when applied to an 
> InputRange? It seems that calling it invalidates the range; in 
> which case what is the recommended way to get a few bytes and 
> keep on advancing.

Doing *anything* to a range invalidates it (or at least you 
should expect it to), a range is read-once. Never reuse a range. 
Some ranges can be saved in order to use a copy of it, but never 
expect a range to be implicitely reusable.

> For instance, to read a ushort, I use
> range.read!(ushort)()
> Unfortunately, it reads a single value.
>
> For now, I use a loop
>
> foreach (element ; range.enumerate) {
>   buffer[i] = range.front;
>   range.popFront();
>   }
>
> Is there a more idiomatic way to do the same thing?

Two ways, the first one being for reference:

     import std.range: enumerate;
     foreach (element, index ; range.enumerate) {
         buffer[index] = element;
     }

And the other one

> In Scala, 'take' consumes bytes from the iterator. So the same 
> code would be
> buffer = range.take(N).toArray

Then just do that!

     import std.range, std.array;
     auto buffer = range.take(N).array;

     auto example = iota(0, 200, 5).take(5).array;
     assert(example == [0, 5, 10, 15, 20]);