Re: "+=" (overloads) with custom array slices on both lhs, and rhs ??

[Ali Çehreli via Digitalmars-d-learn]

On 9/5/21 12:43 PM, james.p.leblanc wrote:

> I have constructed a custom array type that works, but is missing
> correct functioning on some operator overloads.
With its old, new, and newest styles; and support for multi-dimensional 
use cases; operator overloading can be difficult to get right. Here is a 
one-dimensional case that works:

struct MyArray(T) {
  T[] elements;

  this(size_t length) {
    this.elements.length = length;
  }

  size_t opDollar() const {
    return elements.length;
  }

  auto opSliceOpAssign(string op)(T value, size_t beg, size_t end) {
    auto slice = elements[beg .. end];
    mixin (format!q{
        slice[] %s= value;
      }(op));
    return slice;
  }

  // For the entire range of elements
  auto opSliceOpAssign(string op)(T value) {
    // Dispatch to the other one
    return this.opSliceOpAssign!op(value, 0, elements.length);
  }
}

import std.stdio;
import std.format;

void main() {
  auto m = MyArray!(int)(10);

  m[2 .. 5] += 42;
  writeln(m);

  m[4 .. $] -= 100;
  writeln(m);

  m[] *= 2;
  writeln(m);
}

Ali