Proposal: user defined attributes

[deadalnix]

Le 22/03/2012 03:05, Andrei Alexandrescu a écrit :
> On 3/21/12 6:02 PM, deadalnix wrote:
>> Le 21/03/2012 17:22, Andrei Alexandrescu a écrit :
>>> On 3/21/12 11:17 AM, Timon Gehr wrote:
>>>> On 03/20/2012 10:36 PM, deadalnix wrote:
>>>>> Even the propagation of pure, @safe, nothrow and const that has been
>>>>> discussed recently can be done with that feature.
>>>>>
>>>>
>>>> I'm sceptical. How would that work exactly?
>>>
>>> I, too, am highly skeptical. For one thing these attributes must be made
>>> part of the type and have deep connections with code semantics.
>>>
>>> Andrei
>>
>> That is the point. The property must be able to manipulate what is
>> qualified. This is the point of AOP.
>
> Problem is you'd need a ton of hooks to e.g. prevent mutation in const
> methods, or do attribute inference as the compiler does now.
>
>> If you let me some time, I could write a proposal. BTW, this is probably
>> something we don't want to rush in, but I'm sure it definitively worth
>> it.
>
> Honest, I have zero enthusiasm for adding AOP to D right now. But I
> agree it would be an interesting project to see what it would take to
> implement something of the power of pure or const starting from zero
> knowledge.
>

I think we have a misunderstanding here. I wasn't talking about 
reimplementing const or pure. I was talking about propagating them to 
overriden method (a way more easier task). I was talking about 
implementing the recently discussed behavior of override, not actually 
reimplementing const or pure. Not that that wouldn't be possible, but it 
would require a massive amount of work and a very cooperative compiler.

Inference isn't possible with an attribute system.

This is less impressive, but more realistic goal. And that is quite easy 
to achieve.

>> Have you seen what a project like lombok can do ?
>
> This? http://projectlombok.org/ I'll take a look, thanks.
>

Yes.