property += operator

[Dlang User]

On 5/10/2018 1:43 PM, SrMordred wrote:
> struct T
> {
>      int x;
>      @property ref X(){ return x; }
>      @property X(int v)
>      {
>          x = v;
>      }
> }
> 
> T t;
> t.X += 10;
> 
> The setter 'x = v' are not executed because i´m returning the reference 
> of x.
> And without the 'ref' the compiler complains because 'x' is not a lvalue.
> 
> Any solution to make it work like native arr.length+=10 works?
> 
> ( I Thought on returning a struct with "+=" operator but it is a strange 
> solution )

I am relatively new to D and I was under the impression that that was a 
limitation of @property functions.

But, re-reading the language reference, it gave this example (it returns 
something from the write property, which seems odd), I modified to add 
refs, and then it seems to work, but I am not sure if it is correct or not:

import std.stdio;

struct Foo
{
     @property ref int data() { return m_data; } // read property

     @property ref int data(int value) { return m_data = value; } // 
write property

   private:
     int m_data;
}

void main()
{
	Foo f;
	f.data = 5;
	f.data++;
	f.data+= 2;
	writeln(f.data);
	
}