This came to mind while working on a set of containers.
@safety often comes with a performance cost. For example, any
container that wants to give out a range or iterator has to have
a ref-counted or GC allocted payload to ensure safety. In a
high-performance context though, the performance hit may be
unacceptable.
It's fairly easy to make a container that toggles it's
implementation between ref-counted, GC, or raw pointers/arrays,
based on a template parameter. This would allow a single
container to be used in both performance sensitive and safe
contexts (in theory). The only problem would be the lack of
actual @safe annotations on the container, as they would only be
applicable to one variant, and otherwise cause a compile-time
error.
One solution could be this:
struct Container(T, bool safetyOn = true)
{
static if(safe)
RefCounted!(T[]) data;
else
T[] data;
auto opSlice() @safe(safetyOn) {
return Range(data, 0, data.length);
}
}
A similar solution could be applied to @nogc as well.
