C++ Logo

STD-PROPOSALS

Advanced search

Subject: Re: [std-proposals] Make class template parameters available externally
From: Sebastian Büttner (sebastian.buettner_at_[hidden])
Date: 2019-10-30 19:09:37


I don't think that the meaning is consistent here. Declaring something
private isn't the same as not declaring it at all.

Also: how is declaring a template parameter private/public affecting
inheritance? Is the behavior consistent with class member access
control? Is a private declared template parameter of class B not
accessible in a derived class D? Can I declare a template parameter
protected then?

    template<public class first_param, private class second_param>
    class B
    { /* ... */ };

    class D: public B
    {
     Â  // is first_param accessible here? is second_param accessible or not?
    };

If you give this feature the same name as class member access control
users will think likely expect the same behavior and every unreasonable
deviation will be observed as inconsistency.

Sebastian

On 31.10.19 00:56, Jake Arkinstall wrote:
> There are keywords with a consistent meaning: public and private. I'd
> prefer those.
>
> On Wed, 30 Oct 2019, 23:43 Sebastian Büttner via Std-Proposals,
> <std-proposals_at_[hidden]
> <mailto:std-proposals_at_[hidden]>> wrote:
>
> I very much dislike reusing existing keywords with established
> meaning
> for an entirely different purpose.
> Even though i suspect that this is just a strawmen syntax i don't
> think
> on the other hand that the suggestion is important enough to
> justify a
> new keyword.
>
> Sebastian
>
> On 30.10.19 23:48, Bjorn Reese via Std-Proposals wrote:
> > On 10/30/19 10:49 PM, Ville Voutilainen via Std-Proposals wrote:
> >
> >> If I then _don't_ want to expose such a template parameter
> name, what
> >> do I do?
> >
> > The proposal could make it opt-in instead of opt-out. That would not
> > expose existing template parameters without the consent of the
> > template author. For example:
> >
> > template <explicit class value_type,
> >           explicit class allocator_type>
> > struct vector {
> > };
> --
> Std-Proposals mailing list
> Std-Proposals_at_[hidden] <mailto:Std-Proposals_at_[hidden]>
> https://lists.isocpp.org/mailman/listinfo.cgi/std-proposals
>



STD-PROPOSALS list run by std-proposals-owner@lists.isocpp.org

Standard Proposals Archives on Google Groups