Specifying C++ symbols in C++ namespaces

[Adam Wilson]

On Sat, 05 Apr 2014 13:47:32 -0700, Walter Bright  
<newshound2 at digitalmars.com> wrote:

> On 4/2/2014 3:07 PM, Walter Bright wrote:
>> One downside of this proposal is that if we ever (perish the thought!)  
>> attempted
>> to interface to C++ templates, this design would preclude that.
>
> Yes, this seems to be a fatal flaw. Another design that has evolved from  
> these discussions and my discussions with Andrei on it:
>
>      extern (C++, namespace = A.B) { void foo(); void bar(); }
>      extern (C++, namespace = C) void foo();
>
>      bar();  // works
>      A.B.bar(); // works
>      foo(); // error: ambiguous
>      C.foo();   // works
>
>      alias C.foo foo;
>      foo();  // works, calling C.foo()
>
> I really think the namespace semantics should be attached to the  
> extern(C++) rather than be a separate pragma. Having the namespace=  
> thing means that namespace isn't a keyword, and provides a general  
> mechanism where we can add language specific information as necessary.

This seems like a reasonable way to interop with C++ namespace in a D way.  
I also think that it is something that we should do ASAP. I know that for  
Aurora, I will not be able to add complete DirectX support until the C++  
namespace interop problem is solved. Specifically because the highly  
optimized DirectXMath functions are inside a namespace. I do not consider  
pre-mangling a solution, it's a hack for something that is quite common in  
C++, and it's fragile.

-- 
Adam Wilson
GitHub/IRC: LightBender
Aurora Project Coordinator