[boost] Re: is_abstract update

From: David Abrahams (dave_at_[hidden])
Date: 2004-12-04 09:14:30

John Maddock wrote:
> Following on from the recent discussion, we now have:
> 
> BOOST_NO_IS_ABSTRACT added to the config system, this is likely to cause 
> some new failures with config_test.cpp until we get the macro added to 
> those compiler config files that need it (although Gcc, Visual C++, 
> Borland C++ are already taken care of).
> 
> is_abstract no longer uses SFINAE when BOOST_NO_IS_ABSTRACT is defined, 
> instead it defaults to the same value as is_polymorphic: the rationale 
> is that "true" is the safe default (if there is one), but since 
> non-polymorphic types obviously can't be abstract,

   struct X
   {
       protected:
           X();
           ~X();
   };

Not abstract?  I guess the trait can't detect that one anyway, though.

-- 
Dave Abrahams
Boost Consulting
http://www.boost-consulting.com