[dmd-beta] rvalue references

[Don Clugston]

On 13 April 2012 20:14, Jonathan M Davis <jmdavisProg at gmx.com> wrote:
> On Friday, April 13, 2012 18:38:53 Andrej Mitrovic wrote:
>> On 4/13/12, Jonathan M Davis <jmdavisProg at gmx.com> wrote:
>> > On Thursday, April 12, 2012 23:24:17 Andrej Mitrovic wrote:
>> >> Currently you don't have to use address-of operator if you mark the
>> >
>> >> extern(C) function as taking ref:
>> > I consider that to be non-issue. You're calling C code. It's normal to
>> > then
>> > have to use C constructs. And arguably, while calling C code shouldn't be
>> > hard, it _shouldn't_ be pretty, because it's inherently unsafe.
>>
>> Another benefit of allowing in/out/ref is that it serves as good
>> documentation. Microsoft has been using this idiom for years:
>>
>> http://msdn.microsoft.com/en-us/library/dd162477%28v=vs.85%29.aspx
>> http://msdn.microsoft.com/en-us/library/dd144943%28v=vs.85%29.aspx
>> http://msdn.microsoft.com/en-us/library/dd183370%28v=vs.85%29.aspx
>>
>> Being able to mark C function parameters with actual D keywords is a
>> win, imho. It might not make much sense to allow e.g. 'lazy', but
>> in/out/ref is fine.
>>
>> If you want to break code, they you obviously must be willing to put
>> the effort into fixing existing libraries. You can't have Walter & co.
>> advertise the language as stable and then completely break existing
>> code between releases. It would be pure irony to ban this feature
>> considering how Walter already made a thread about stopping breaking
>> code between releases.
>
> As of right now, it's questionable whether this is an intended feature or
> whether it just so happens to work. If it just so happens to work, then it's a
> bug, and just like any bug, when it's fixed, any code relying on it will break.

Interestingly, the ref int[3] idiom is documented as working, under
'interfacing with C'.
Anything beyond that seems to be undefined.
That page seems to document dynamic arrays as _not_ working --
certainly as having no C equivalent.