From: E. Gladyshev (egladysh_at_[hidden])
Date: 2003-10-04 12:38:11
Apparently it is me who is missing something.
I've never used it before. What is variant?
Eugene
--- Joel de Guzman <djowel_at_[hidden]> wrote:
> Sounds like a variant to me. What am I missing?
>
> --
> Joel de Guzman
> http://www.boost-consulting.com
> http://spirit.sf.net
>
>
> E. Gladyshev <egladysh_at_[hidden]> wrote:
> > Just wondering does boost have something similar to C unions
> > so that you could create heterogenious containers?
> >
> > Something like the following working pseudo-code
> >
> > template < typename Types >
> > struct union2
> > {
> > typedef typename boost::mpl::at_c<Types, 0 >::type type1;
> > typedef typename boost::mpl::at_c<Types, 1 >::type type2;
> >
> > union2() : obj_(0)
> > {
> > }
> > union2( const union2<Types>& l ) : obj_(0)
> > {
> > create( l.t_ );
> > copy( l.obj_ );
> > }
> > virtual ~union2()
> > {
> > free();
> > }
> >
> > void create( size_t t )
> > {
> > free();
> > t_ = t;
> > switch( t_ )
> > {
> > case 0:
> > obj_ = new type1;
> > break;
> >
> > case 1:
> > obj_ = new type2;
> > break;
> >
> > default:
> > throw;
> > }
> > }
> >
> > private:
> > size_t t_;
> > void *obj_;
> > void free()
> > {
> > if( !obj_ ) return;
> > switch( t_ )
> > {
> > case 0:
> > delete static_cast<type1*>(obj_);
> > break;
> >
> > case 1:
> > delete static_cast<type2*>(obj_);
> > break;
> >
> > default:
> > throw;
> > }
> > obj_ = 0;
> > }
> >
> > void copy( void* obj )
> > {
> > switch( t_ )
> > {
> > case 0:
> > *static_cast<type1*>(obj_) = *static_cast<type1*>(obj);
> > break;
> >
> > case 1:
> > *static_cast<type2*>(obj_) = *static_cast<type2*>(obj);
> > break;
> >
> > default:
> > throw;
> > }
> > }
> > };
> >
> > main()
> > {
> > typedef notus::union2< boost::mpl::vector2<char, short> > my_union;
> >
> > std::vector< my_union > gv;
> >
> > my_union u(0);
> > my_union u1(1);
> > gv.push_back( u );
> > gv.push_back( u1 );
> > }
> >
> >
> > Eugene
> >
> >
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