Re: [boost] New dependency report

Subject: Re: [boost] New dependency report
From: Andrey Semashev (andrey.semashev_at_[hidden])
Date: 2014-06-13 12:42:01

On Friday 13 June 2014 09:27:04 Eric Niebler wrote:
> I am in favor of adding an mpl::tag_of metafunction which retrieves the
> tag type of the passed mpl entity.

I think, mpl::tag already implements that. See mpl/tag.hpp.

> It can be specialized for
> std::integral_constant to do the right thing. In addition, it would fix
> the issues raised here:
> 
> http://lists.boost.org/Archives/boost/2009/01/147045.php
> 
> and here:
> 
> https://svn.boost.org/trac/boost/ticket/7192
> 
> I think in the C++11 world, boost type_traits should *all* inherit from
> std::true_type. That's easily accomplished by aliasing mpl::true_ to
> std::true_type. It fixes everything.

Well, technically that would still be a breaking change, even though a 
relatively safe one. I think if the goal is to add support for 
std::integral_constant to MPL, it can be achieved with a less radical 
solution.