Re: [boost] [type_traits] is_base_of<B, D> should work when B is incomplete

Subject: Re: [boost] [type_traits] is_base_of<B, D> should work when B is incomplete
From: Gavin Lambert (gavinl_at_[hidden])
Date: 2016-03-03 23:10:03

On 4/03/2016 12:24, Daniel Frey wrote:
> But if std::is_base_of is available, boost::is_base_of should surely
> just forward to it, so only those compilers that don’t have it (aka
> mostly pre-C++11 compilers) are of interest here. Maybe lifting the
> restriction (and using an alternative implementation) should be
> conditional, only to be guaranteed by boost::is_base_of when
> compiling with C++11 or newer?

I think the operative question is, why would you use it?

If you know you have C++11 compilers always, then use std::is_base_of 
and your code can use complete or incomplete types as you wish.

If you don't know you have C++11 compilers always, then use 
boost::is_base_of and restrict yourself to complete types.

If you're using the Boost version to broaden compiler support, then your 
code would not compile (or would produce different results) depending 
which environment you compiled it in.  So you could end up with code 
that works in development but fails in production.