Re: [boost] is_virtual_base_of ?

Subject: Re: [boost] is_virtual_base_of ?
From: Robert Ramey (ramey_at_[hidden])
Date: 2009-03-11 16:58:01

The problem is that Base needs the default constructor

Daniel Frey wrote:
> On 11.03.2009, at 19:18, Robert Ramey wrote:
>
>> My current version - checked into the trunk at
>> boost/serialization/is_virtual_base_of.hpp is attached.  I think it
>> addresses the points mentioned here.
>>
>> I can fix the case that causes me problems by adding a default
>> constructor
>> which is never called.  That doesn't help for the generic case
>> though.  I'm
>> guessing that type traits has lots of situations where members are
>> declared
>> and never called.
>
> You probably misunderstood the idea, as it is really generic. The idea
> is to add a declaration (without a definition) of X's ctor (or any
> other generated methods that cause you trouble). To be more precise:
>
> Index: boost/serialization/is_virtual_base_of.hpp
> ===================================================================
> --- boost/serialization/is_virtual_base_of.hpp (revision 51709)
> +++ boost/serialization/is_virtual_base_of.hpp (working copy)
> @@ -29,7 +29,7 @@
>  template<typename Base, typename Derived>
>  struct is_virtual_base_of_impl
>  {
> -    struct X : Derived, virtual Base {};
> +    struct X : Derived, virtual Base { X(); };
>      BOOST_STATIC_CONSTANT(bool, value = sizeof(X)==sizeof(Derived));
>  };
>
> HTH, Daniel
>
> _______________________________________________
> Unsubscribe & other changes:
> http://lists.boost.org/mailman/listinfo.cgi/boost