Optional tags and attributes

[Stanislav Blinov]

On Saturday, 18 January 2014 at 03:02:45 UTC, Steven 
Schveighoffer wrote:

> I was about to respond with a similar point, but it seems you 
> are understanding now how the nothrow inference works :)

O:)

> I can't think of a correct way to do this without repeating 
> code, since it has to be polymorphic (and therefore not a 
> template), nothrow inference only works on templates.
>
> The idea to be able to attach attributes/annotations based on 
> compile-time introspection would be a worthy addition to the 
> language IMO, but I really don't like the syntax you have 
> outlined (I see you don't like it either).

No, I actually quite like that C++ syntax, although AFAIK it's 
only "special" in that one particular occasion. I was mentioning 
that syntax doesn't matter because I wanted to make sure I'm not 
pushing any C++ features here, just making a point about a nice 
usability feature :)

> Especially if you have to do all the attributes this way.

> I think a "use the attributes of X" would be a general enough 
> tool.
>
> Something like:
>
>  void thisIsSoPolymorphic() attrOf(T.foo)

And here is where I would disagree. Fine-grained control over 
each attribute is more important. For example, the function may 
be always nothrow (say I handle all the exceptions in the world 
or assert(0) on what's left; D helpfully doesn't consider 
assert(0) as throwing :) ), but it may be conditionally pure or 
safe.