Proposal: user defined attributes

[Kapps]

On Sunday, 18 March 2012 at 01:48:07 UTC, Walter Bright wrote:
> On 3/17/2012 6:39 PM, Manu wrote:
>> I'm sure C# already answers all these questions. It has 
>> precisely the same set
>> of issues associated.
>
> C# doesn't have RAII, immutable, nor the notion of 
> threadlocal/shared types.

It has threadlocal using the [ThreadLocal] attribute which gets 
implemented by the compiler.

In C#, all attributes live inside the TypeInfo/MethodInfo/etc for 
the class/struct/method/field/parameter. I don't see this being a 
problem. I can't think of good use cases where an 
attribute/annotation should be per-instance at all, particularly 
with the compile-time power that D has, whereas C# does not have 
any. Honestly, most uses of attributes in D would be done at 
compile-time, and I think that's acceptable until/if runtime 
reflection is put in. If it is needed, it can live inside 
TypeInfo/MethodInfo, but is (imo) absolutely not needed on a 
per-instance basis. This is the job of fields or interfaces.