Optional tags and attributes

[H. S. Teoh]

On Fri, Jan 17, 2014 at 10:02:44PM -0500, Steven Schveighoffer wrote:
> On Fri, 17 Jan 2014 21:50:07 -0500, Stanislav Blinov
> <stanislav.blinov at gmail.com> wrote:
> 
> >On Saturday, 18 January 2014 at 02:38:28 UTC, H. S. Teoh wrote:
> >
> >>What's wrong with just letting the compiler infer the maximal function
> >>attributes?
> >
> >...
> >
> >>Sadly, this only works for template functions currently -- so I still
> >>had to annotate the various method()'s by hand, but if you were to turn
> >>them into template functions too, their attributes will also be inferred
> >>automatically.
> >
> >Oh, I see now where it went the wrong way. From my own example, of
> >course :)
> >
> >Surely I was meaning:
> >
> >class Careful(T) {
> >//...
> >   void thisIsSoPolymorphic() nothrow(isNoThrow!(T.foo)) { ... }
> >//...
> >}
> >
> >Something to that extent. So that yes, the function itself is not
> >a template.
> 
> I was about to respond with a similar point, but it seems you are
> understanding now how the nothrow inference works :)
> 
> 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.

See https://d.puremagic.com/issues/show_bug.cgi?id=10329 and the
associated pull, which has just been merged. I haven't tested it myself
yet, but it would appear that methods inside template classes should now
have their methods' attributes inferred too?

If so, then you can just take out the nothrow clause and it should work?
(But since I haven't tested this yet I could be wrong.)


> 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). 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)
[...]

Hmm. Would functionAttributes and SetFunctionAttributes in std.traits
help somehow? Not sure how you might actually use them to declare
methods with desired attributes, though. But maybe there's a way.


T

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