confusion about structs

[Jonathan M Davis]

On Monday, September 26, 2011 00:04:48 Andrej Mitrovic wrote:
> This should make things clearer for you:
> 
> unittest
> {
>     auto h1 = get(1);
>     auto h2 = get(2);
> 
>     assert(h1 is h2);  // both reference the same array
> }
> 
> Field initialization is only done once (once per thread, or if a field
> is shared once on app start) and not each time you call the
> constructor.

Ah. Yes. Okay. There isn't a bug here then (at least not in the compiler). The 
problem is that if you don't assign app in the constructor, it uses the exact 
same value as is in App.init - there is no copying going on - so every 
instance (or at least every instance on each thread) then points to exactly 
the same array. That's definitely something that could be easy to miss if 
you're not careful and is probably a sign that mutable arrays shouldn't 
generally be in the init property of structs (unless they're empty).

- Jonathan M Davis