Re: [Boost-users] variant: bounded types derive from same base class

Subject: Re: [Boost-users] variant: bounded types derive from same base class
From: Igor R (boost.lists_at_[hidden])
Date: 2009-08-03 08:56:07

> typedef boost::variant<D1, ... , Dn> Â ABCDerived;
>
> and the user could write visitors to visit ABCDerived objects,
> here the user is enforced to implement all cases in the visitor.
>
> but then the function f expects ABC objects. Can I still do:
>
> void f( const ABC& abc )
> {
> Â  // how to write code to use the visitors with abc ?
> }

struct YourVisitor : boost::static_visitor<functor return type>
{
  result_type operator()(const D1 &d1)
  {...}
  result_type operator()(const D2 &d1)
  {...}
  // etc. for all the type in the variant
};

then:

boost::apply_visitor(YourVisitor(), yourVariant);