DIP6: Attributes

[Steven Schveighoffer]

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.

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#.

-Steve