DIP6: Attributes

[Ary Borenszweig]

Andrei Alexandrescu wrote:
> Steven Schveighoffer wrote:
>> On Tue, 04 Aug 2009 12:23:41 -0400, Andrei Alexandrescu 
>> <SeeWebsiteForEmail at erdani.org> wrote:
>>
>>> Steven Schveighoffer wrote:
>>>> On Tue, 04 Aug 2009 09:45:51 -0400, grauzone <none at example.net> wrote:
>>>>
>>>>> Steven Schveighoffer wrote:
>>>>>> don't think it's worth adding them until we can have full 
>>>>>> reflection capabilities so we can get at elements of code and 
>>>>>> therefore get the annotations associated with it.  I see much more 
>>>>>> usefulness for annotations as reflection hints than as a 
>>>>>> replacement for keywords.
>>>>>
>>>>> But we already have full reflection. It's called __traits. You can 
>>>>> build a serialization library or "proper" (user friendly?) 
>>>>> reflection on top of it.
>>>>  I think you are the 1 millionth person to say it, and yet we still 
>>>> do not have a "user friendly" reflection system.  Why is that?  
>>>> You'd think that if it could be done, somebody would have done it by 
>>>> now.
>>>
>>> The reality is there's quite few of us. D is not in the stage where 
>>> if something could be done, somebody somewhere has done it or is 
>>> working on it.
>>>
>>
>> That's understandable, nobody can expect a language as young as D to 
>> have everything.
>>
>> But in reality, I think the *theory* that everything is there to build 
>> a reflection system is only proven when it actually happens.  I'm sure 
>> when the enterprising person or persons go to develop it, they will 
>> find pieces missing from the static reflection system.
> 
> Exactly. I'm absolutely sure there are quite a few things needed here 
> and there. I can assure you I'll push hard for those.
> 
>> So my point is that adding annotations before reflection works and is 
>> implemented makes little sense to me, because the usage of them will 
>> be crippled by the fact that reflection isn't complete.
>>
>> What I'd like to see is something like this possible:
>>
>> void foo (int timeout, string bar, float f = 4.0);
>>
>> void foo(int timeout);
>>
>> call!(foo)("timeout=5,bar=\"hello\"");
>>
>> Taking into account the default value of f, what the parameters are 
>> named, and which overload to call.  I could certainly do it with C#.
> 
> This is interesting. It means we'd need reflection for parameter names, 
> which currently does not exist.

Why do it with strings? Why not

call!(foo)(5, "hello")

with varaidic args?