typed vtable

[Denis Koroskin]

On Tue, 18 Nov 2008 17:17:36 +0300, Michel Fortin  
<michel.fortin at michelf.com> wrote:

> On 2008-11-17 13:56:55 -0500, Harry Vennik <htvennik at zonnet.nl> said:
>
>> Hi,
>>  One of the things D claims is that it eliminates the need for IDL. And  
>> yeah, it does a lot in that direction, but I found something that's  
>> missing while trying to actually implement some sense of RPC...
>>  To get a good view of an interface that can be used to construct the  
>> necessary stub code, you need to have a typed vtable. And D almost  
>> provides it... You can get the untyped vtable, you can get a typed list  
>> of virtual function overloads by name, and you can get the names of all  
>> interface members... So you can get all what's needed, except that  
>> there is no way to know the vtable index of a member function!!!
>>  My proposal to fix this is to allow an expression like:
>>  __traits(getVirtualFunctions, T)           // no second argument!
>>  where T is an interface or class type (or an expression of such a  
>> type). Such an expression should then return all virtual member  
>> functions in vtable order, thus making it possible to relate the  
>> function itself to its vtable index.
>
> Personally, I had to work around the same problem in the D/Objective-C  
> bridge and thus I could probably simplify a few things by having this,  
> except that what I need in my case is always the vtable index of a  
> particular function. I guess it could be implemented from the above  
> __traits syntax, but I'd wish for a simpler solution to my problem, such  
> as:
>
> 	__traits(getVTableIndex, T.foo);
>
> along with a way to check if a function is virtual, possibly by checking  
> they're not final:
>
> 	static if (is(T.foo == final)) ...;
>
> This way I could build a pointer template-struct to a virtual member  
> function (without knowing the target object in advance as with  
> delegates).
>
>

What if class T has multiple foo() overloads, half of which are virtual  
and half are not?