Efficient way to pass struct as parameter

[Seb]

On Tuesday, 2 January 2018 at 18:21:13 UTC, Tim Hsu wrote:
> I am creating Vector3 structure. I use struct to avoid GC. 
> However, struct will be copied when passed as parameter to 
> function
>
>
> struct Ray {
>     Vector3f origin;
>     Vector3f dir;
>
>     @nogc @system
>     this(Vector3f *origin, Vector3f *dir) {
>         this.origin = *origin;
>         this.dir = *dir;
>     }
> }
>
> How can I pass struct more efficiently?


If you want the compiler to ensure that a struct doesn't get 
copied, you can disable its postblit:

  @disable this(this);

Now, there are a couple of goodies in std.typecons like 
RefCounted or Unique that allow you to pass struct around without 
needing to worry about memory allocation:

https://dlang.org/phobos/std_typecons.html#RefCounted
https://dlang.org/phobos/std_typecons.html#Unique

Example: https://run.dlang.io/is/3rbqpn

Of course, you can always roll your own allocator:

https://run.dlang.io/is/uNmn0d