Re: [boost] [type_traits] Big changes in develop

Subject: Re: [boost] [type_traits] Big changes in develop
From: Peter Dimov (lists_at_[hidden])
Date: 2015-05-28 12:38:21

John Maddock wrote:
> > remove_cv_ref<T> (remove_cv<remove_reference>)
>
> I would be inclined to call that remove_cv_reference ?

remove_cv_ref is the already established name; everyone uses it. Boost has 
two such, one in base_from_member, another in function_types/example. 
remove_cv_ref: 3080 results in Google, remove_cv_reference: 6 results. 
Although I wouldn't be surprised if we get std::remove_cv_reference at some 
point, as one of those 6 results is in the LWG issue list.

> > combine_cv<T, U> (copies the cv qualifiers from U to T)
>
> See https://svn.boost.org/trac/boost/ticket/3970

copy_cv works too.

> > common_arithmetic_type<T, U> (for arithmetic or enum types, their common 
> > type per "usual arithmetic conversions")
> > composite_pointer_type<T, U> ( the "composite pointer type" per the 
> > standard, that is, the pointer type to which both T and U will convert)
> >
> > Should we add those traits to the library proper, or is it better for 
> > them to remain implementation details? The first three seem to be 
> > rediscovered on a daily basis.
>
> IMO +1 on the first three, much less sure about the last 2.

The last two appear worthy because (a) they implement things that are 
specified in the standard; both "usual arithmetic conversions" and 
"composite pointer type" are in [expr] and (b) they deserve their own tests, 
and it's a bit odd to test implementation details. But either way is fine 
with me.

> Care to submit a PR?

I'm not at the PR point yet, need to clean up the implementation and check 
against the existing tests (which are pretty slim by the way) first.