Re: [boost] SFINAE yes_type and no_type

Subject: Re: [boost] SFINAE yes_type and no_type
From: Edward Diener (eldiener_at_[hidden])
Date: 2011-04-16 09:55:36

On 4/15/2011 11:13 AM, Jeroen Habraken wrote:
> Hi,
>
> Is there a specific yes_type and no_type inside boost that I should be
> using when writing a SFINAE test? There seem to be quite a few defined
> already and reinventing the wheel (albeit it being trivial) again
> doesn't make sense.

For the Boost developer there is:

#include <boost/type_traits/detail/yes_no_type.hpp>

you then have:

::boost::type_traits::yes_type
::boost::type_traits::no_type

Of course the intention of 'detail' for a library is that the code 
should only be used by that library, but I think, in this case, it is 
allowable for other Boost library developers to use it also.

But since this is a part of type traits detail it is not meant to be 
used outside of a Boost library ( ie. by end-users ).

It would perhaps be better if ::boost::type_traits::yes_type and 
::boost::type_traits::no_type were put into its own utility classes to 
make it more apparent that Boost library developers and end-users of 
Boost could use it.

OTOH it might be presumptuous of me to suggest that it be used at all 
outside of type traits, but I have used it in my own TTI sandbox library 
anyway since type traits itself is used heavily there.