Re: [boost] feature request for optional

From: Sascha Krissler (boost-dev_at_[hidden])
Date: 2006-08-06 12:43:37

> >Besides an out of line boost :) dynamic_bitset
>
> Could you please explain that?

Basically this:

template <typename Key, typename Value, typename HashFn>
class PerfectHash {
        dynamic_bitset foo;
        std::vector<std::pair<Key, Value> > bar;
        Value get(Key k) {
                if (foo[HashFn::baz(k)]
                      && bar[HashFn::baz(k)].first == k
                ) {
                        return bar[HashFn::baz(k)].second;
                } else {
                        throw;
                }	
        }
};

out of line means the information whether a certain slot
in the underlying container holds a valid value is not stored
in the container, as it would be the case if i used
boost::optional<std::pair<Key, Value> > as the parameter
to the std::vector template.