Re: std::max: if versus ?:

[Marc Glisse <marc dot glisse at inria dot fr>]

On Sun, 23 Sep 2012, Gabriel Dos Reis wrote:

> On Sun, Sep 23, 2012 at 12:06 PM, Marc Glisse <marc.glisse@inria.fr> wrote:
> > On Sun, 23 Sep 2012, Gabriel Dos Reis wrote:
> >
> > > On Sun, Sep 23, 2012 at 10:09 AM, Marc Glisse <marc.glisse@inria.fr>
> > > wrote:
> > >
> > > > Then that may mean no std::max for vectors, at least until someone makes
> > > > the
> > > > inner type and size of vectors deducible (that would make the vector
> > > > version
> > > > of max more specialized than the generic one and allow overloads without
> > > > touching the generic function). Which isn't that bad, people are big
> > > > enough
> > > > to write (x<y)?y:x themselves...
> > >
> > >
> > > I do not understand why you can't have a syntax such as  __vector<T,N>
> > > those extensions.   If that syntax isn't there, you should consider adding
> > > it.  It is a natural thing to have.
> >
> >
> > The syntax exists (though it is ugly): T __attribute__((vector_size(N))).
>
> that is why I suggested __vector<T,N>.

So you were only suggesting it as a syntax and not as an internal 
representation. I guess I can look at a nicer syntax once the feature 
actually works.

> > What doesn't work currently is that T and N are not deducible, in a template
> > context. One possibility would be to make them deducible
>
> Yes.  That is a more scalable solution, IMO.
>
> >  (sounds like duplicating a bit of template machinery).
>
> Why?

For array<T,N>, deduction works. For attributes, reading PR35758, there is 
going to be a lot of work to make it work.

--
Marc Glisse