[boost] Re: mpl/loki

From: David Abrahams (dave_at_[hidden])
Date: 2003-07-12 18:12:53

Aleksey Gurtovoy <agurtovoy_at_[hidden]> writes:

> David Abrahams wrote:
>> Aleksey Gurtovoy <agurtovoy_at_[hidden]> writes:
>>
>> > IMO we should just stop using 'void_' for internal purposes and give it
>> > up to users :).
>>
>> I am still unsure about 'void_' being better than 'nil' or
>> 'null'....  Users already have a type, 'void', which means void.
>
> ... in conventional run-time programs. Unfortunately, 'void' is not
> special for metaprograms, many of which have a need to routinely
> manipulate it along with all other built-in types. 'mpl::void_'
> addresses this issue.
>
>> There's no correspondence between void_ and void the way there is
>> between bool_ and bool.
>
> 'void_' in MPL plays a role very similar to a role of 'void' in the
> core language.  So, conceptually, there is a correspondence.

But that's only true as long as void_ is being used for internal
purposes.  Once you "give it up to users" as you suggest, it loses
that correspondence, and we'll have some other internal name which
has that correspondence to void.

> Personally, I appreciate the analogy, dislike 'null'/'nil'/etc. for
> the lack of such, and would like to keep the name.

Makes little sense to me, especially after the "give up", but maybe
that's just me.

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com