Objective-D, reflective programming, dynamic typing

[Andrei Alexandrescu]

Christopher Wright wrote:
> Andrei Alexandrescu wrote:
>> Christopher Wright wrote:
>>> Andrei Alexandrescu wrote:
>>>> void foo_templated(T...)(T args)
>>>> {
>>>>    Variant[args.length] dynatyped;
>>>>    foreach (i, arg; args) dynatyped[i] = arg;
>>>>    return foo(dynatyped);
>>>> }
>>>> void foo(Variant[] dynatyped...)
>>>> {
>>>>    ...
>>>> }
>>>>
>>>> Andrei
>>>
>>> Okay, that's a reasonable solution, except that it doesn't work with 
>>> interfaces. I already submitted a bugzilla entry that you should be 
>>> able to create a Variant[] from D varargs, but that still requires 
>>> writing a wrapper function.
>>
>> A Variant[] is difficult to create from TypeInfo[] + void* varargs 
>> because vital information has already been lost. That's why I'm saying 
>> we better fix the situation by e.g. implementing opImplicitCast. 
>> Please, let's leave void* alone.
>>
>> Andrei
> 
> I don't find that this is the case. I implemented a Variant type that 
> can be created from a void* and a typeinfo -- I had to, since tango's 
> Variant doesn't support this (and, incidentally, because there is no way 
> to get a representation of the data inside a tango Variant).
> 
> What information did you find that you needed but is not available in 
> TypeInfo?

To have constant-type dispatching without limitations you need the 
static type information.

Andrei