Re: boost weak pointers and boost optional
On Jul 17, 11:21 am, Thant Tessman <thant.tess...@gmail.com> wrote:
In the case of weak pointers, it would have to look more like:
struct nothing {};
template <typename T>
struct weak_pointer {
/* ...*
typename boost::variant<nothing,shared_ptr<T> > Optional;
Optional lock() const;
/* ... */
}
Right. So how does user code look like?
1.
Optional opt = wp.lock();
if( shared_ptr<T>* p = boost::get< shared_ptr<T> >( &opt ) )
{
// use **p
}
else
{
// do not use p
}
2.
Optional opt = wp.lock();
try
{
shared_ptr<T> const& r = boost::get< shared_ptr<T> >( opt );
// use *r
}
catch( boost::bad_get )
{
// ...
}
3.
struct visitor
{
typedef void result_type;
void operator()( shared_ptr<T> const & p ) const { ... }
void operator()( nothing ) const { ... }
};
boost::apply_visitor( visitor(), wp.lock() );
Which one of these is an improvement?
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