Re: [boost] Formal Review Request: TypeErasure

Subject: Re: [boost] Formal Review Request: TypeErasure
From: Dave Abrahams (dave_at_[hidden])
Date: 2012-06-07 19:47:01

on Thu Jun 07 2012, Steven Watanabe <watanabesj-AT-gmail.com> wrote:

> AMDG
>
> On 06/07/2012 01:27 PM, Dave Abrahams wrote:
>> 
>> on Thu Jun 07 2012, Nevin Liber <nevin-AT-eviloverlord.com> wrote:
>> 
>>> On 7 June 2012 13:41, Dave Abrahams <dave_at_[hidden]> wrote:
>>>
>>>>
>>>> In a nutshell, concept-based-runtime-polymorphism/type-erasure allows
>>>> you to have runtime polymorphism while preserving value semantics.  The
>>>> value of that win is very commonly underestimated.
>>>>
>>>
>>> +1
>>>
>>> So, is there a language feature that could be added to C++17 that would
>>> make implementing type erasure easier?
>> 
>> Yes; concepts :-)
>> 
>
> I don't see how concepts would help.
> Concepts would allow you to check the
> requirements, but I don't think there's
> any way to build a vtable from a concept
> definition.

Not in a library, maybe, but concepts would lay the groundwork for the
necessary language feature; I think it could be a very small extension
on top of concepts.

-- 
Dave Abrahams
BoostPro Computing
http://www.boostpro.com