Hi,

When I use the chunks() template with iota(), for instance, with chunks(2), I can access both r.front and r.back. However, in a range of my own type (named iras in the code below), only r.front is working. I think the error given by r.back is not a bug related to chunks, is it?

import std.array, std.algorithm,
       std.range,
       std.stdio;

void main()
{
  auto rng1 = iota!real(24.0, 1321.0, 16.5).take(8);
  auto rng2 = iras!real(24.0, 1321.0, 16.5).take(8);

  auto noError = rng1.chunks(2)
                     .map!(r =>
                      r.back - r.front);

  assert(noError.equal([16.5, 16.5, 16.5, 16.5]));
  /*
  auto error = rng2.chunks(2)
                     .map!(r =>
                      r.back - r.front);/*

    main.d(18): Error: none of the overloads of template
          `std.range.primitives.back` are callable using
           argument types `!()(Take!(InclusiveRange))`*/
}
/*
 * iras v3
 * (inclusiveRange) Source:
 * https://forum.dlang.org/post/bnnxentwstkjnxkychro@forum.dlang.org
*/

The same problem occurs here:

struct Range(T)
{
  T n = 3;
  bool empty;

  alias back = front;
  auto front() => n.cube - n * 0.5;

  auto popFront() => n += 2;
  auto backFront() => n -= 2;
}

SDB@79

On Thursday, 28 March 2024 at 17:50:17 UTC, Salih Dincer wrote:

It's really nice to solve a problem on your own. Turns out I needed to add save, opSlice, length and opDollar members to the range.

SDB@79