@safe RCSlice with DIP1000 + runtime checks

[rikki cattermole via Digitalmars-d]

On 02/09/2016 11:18 PM, Nick Treleaven wrote:
> Hi,
> I've been working on a proof of concept Reference Counted Slice
> container, based on the one in DIP1000. That one now has opAssign marked
> @system, see:
>
> https://github.com/dlang/DIPs/blob/master/DIPs/DIP1000.md#owning-containers
>
> So I decided to make an RCSlice with a @safe opAssign (and @safe
> destroy, std.algorithm.move). opIndex is no longer a direct member,
> instead indexing RCSlice causes the compiler to create a RCRef temporary
> struct (via alias this), which does have opIndex:
>
> https://github.com/ntrel/stuff/blob/master/typecons/rcref.d
>
> The temporary struct is a private type, returned as an rvalue, so can't
> itself be passed by ref, so it should avoid the paired ref argument case
> mentioned in the above DIP1000 link.
>
> RCRef increments *RCSlice.count on construction and decrements on
> destruction, but first checks that *count is > 1. If this fails, an
> AssertError is thrown. When -noboundschecks is passed, the code assumes
> no safety checks should be made for RCSlice and compiles out all the
> additional counting code.
>
> Of course it would be great to have compile-time checks, so I'm looking
> forward to a DIP for that. But in the meantime this appears to show D
> can have @safe ref-counting now that DIP1000 is underway.
>
> Thoughts?

I've got a much more advanced memory management solution[0].
I'm waiting on DIP1000 implementation before implementing it into it.

But over all I quite like this type approach.

[0] 
https://github.com/rikkimax/alphaPhobos/blob/master/source/std/experimental/memory/managed.d#L255