is(T == function)

[spir]

On 02/10/2011 05:22 PM, Steven Schveighoffer wrote:
> I know this is an old issue, and I found this old bug to describe it (helping
> someone in a D.learn thread): http://d.puremagic.com/issues/show_bug.cgi?id=3464
>
> But my question is, what is the value of T in *expected* usage. The bug gives
> the example:
>
> is(typeof(*T.init) == function)
>
> to test for a function pointer, but I tried this:
>
> is(main == function)
>
> And that doesn't work, but this does:
>
> is(typeof(main) == function)
>
> So, my question is, what is typeof(main)? I tried pragma(msg,
> typeof(main).stringof) and I get "void()()", which doesn't compile.

???
We need types to exist, not typeof's.

> Given how ridiculously special-cased is expressions are anyways, can we just
> define is(T == function) to do something expected? I can't think of a single
> "normal" use case that doesn't involve typeof or init.
>
> I'd like to see either of these work instead of what we have:
>
> is(main == function)
> is(&main == function)
>
> I think the latter would be the most useful, and consistent with delegates,
> especially since we got rid of declaring a function type (not function pointer
> type) in recent times (I think Don did this to prevent some kooky C legacy bug).

Agreed. This would be a step toward stopping function* implementation detail 
leaking into language semantics. The language feature <function> should just 
mean function. (Else, to be consistent, we should be forced to use delegate 
pointers as well, no?)

If can stop and using '&' to pass functions as arguments, then life is good and 
we should use is(main == function). Else, vote rather for is(&main == function) 
as well, for better consistency.

Denis
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