A Refcounted Array Type

[Max Klyga via Digitalmars-d]

I thought that delete is deprecated, yet here Walter himself promotes a 
solution that uses it.
Can we *PLEASE* finally deprecate things that are supposed to be 
deprecated and remove things that are supposed to be removed?

On 2015-02-23 22:15:46 +0000, Walter Bright said:

> This is pretty straightforward. More could be done:
> 
> 1. small array optimization
> 2. support for ranges as constructor args
> 3. present a range interface
> 4. support for malloc/free instead of GC
> 5. bounds checking
> 6. the array[] and the count could be allocated together
> 7. array[] could be just a pointer
> 
> but the basic idea is there, I didn't want to hide it behind all the 
> other flesh a professional type would have.
> 
> Note the return in opIndex(). This is DIP25 at work!
> 
> Compile:
>      dmd rcarray -unittest -main -dip25
> 
> ===========================================
> 
> struct RCArray(E) {
> 
>      this(E[] a)
>      {
>          array = a.dup;
>          start = 0;
>          end = a.length;
>          count = new int;
>          *count = 1;
>      }
> 
>      ~this()
>      {
>          if (count && --*count == 0)
>              delete array;
>      }
> 
>      this(this)
>      {
>          if (count)
>              ++*count;
>      }
> 
>      size_t length()
>      {
>          return end - start;
>      }
> 
>      ref E opIndex(size_t i) return // here's the magic
>      {
>          return array[start + i];
>      }
> 
>      RCArray opSlice(size_t lwr, size_t upr)
>      {
>          RCArray result = this;
>          result.start = start + lwr;
>          result.end = start + upr;
>          return result;
>      }
> 
>    private:
>      E[] array;
>      size_t start, end;
>      int* count;
> }
> 
> unittest
> {
>      static int[3] s = [7, 6, 4];
>      auto r = RCArray!int(s);
>      assert(r.length == 3);
>      assert(r[0] == 7);
>      assert(r[1] == 6);
>      assert(r[2] == 4);
>      assert(*r.count == 1);
> 
>      {
>          auto r2 = r;
>          assert(r2[0] == 7);
>          assert(r2[1] == 6);
>          assert(r2[2] == 4);
>          assert(*r.count == 2);
> 
>          r[1] = 3;
>          assert(r2[0] == 7);
>          assert(r2[1] == 3);
>          assert(r2[2] == 4);
>      }
>      assert(*r.count == 1);
> 
>      auto r3 = r[1 .. 3];
>      r[2] = 9;
>      assert(r3[0] == 3);
>      assert(r3[1] == 9);
> 
>    /+
>      ref int test(ref RCArray!int rr)
>      {
>          return rr[1]; // this gives error
>      }
>     +/
> }