import std.stdio;

import std.range;

​

struct Matrix(T)

{

  private T[][] elements;

  size_t length;

  T* ptr;

  this(size_t length)

  {

    this.length = length * length;

    size_t m = T.sizeof * this.length;

    ubyte[] arr = new ubyte[](m);

    ptr = cast(T*)arr.ptr;

    m /= length;

    foreach(i; 0 .. length)

    {

      size_t n = i * m;

      elements ~= cast(T[])arr[n .. n + m];

    }

  }

  ref T opIndex(size_t i)

  in(i < length)

    => ptr[i];

  auto opDollar() => length;

  auto opSliceAssign(T value, size_t a, size_t b)

  in(a <= length && b <= length)

    => ptr[a..b] = value;

  auto opIndex() => elements;

  auto opIndexAssign(T value)

  {

    foreach(i; 0 .. length)

    {

      ptr[i] = value;

    }

  }  

}

​

void main()

{

  auto arr = Matrix!double(3);

  size_t n;

  foreach(value; iota(0.1, 1, 0.1))

    arr[n++] = value;

  arr[].writefln!"%-(%-(%s %)\n%)\n";

  arr[0..$/2] = 0;   // reset a slice

  arr[].writefln!"%-(%-(%s %)\n%)\n";

  arr[] = 0;             // reset all

  arr[].writefln!"%-(%-(%s %)\n%)\n";

  arr[6..9] = 1;       // set a slice

  arr[].writefln!"%-(%-(%s %)\n%)\n";

}

​