Question

I’ve got a class, memberlist, that contains a std::list of class memberinfo. These represents the peers on a network.

I use the class to add some functionality to the list.

I want to expose some iterators (begin and end) so that outside code can loop through my internal list and read their data. However, I want to have two ways of doing this – one that includes an element for the localhost, and one that doesn’t.

What’s a good way to do this?

I could put the local node first, then have like begin(showlocal=false) just give the second element instead of the first. Or someone suggested storing a pair of with the bool saying if it’s local or not.

Any suggestions on a good way to do this? I’m not too great on advanced STL stuff yet.

Answer 1

Personally I would approach this in a different way and have your memberinfo have a way of telling you if it’s local or not.

That way you’re not specialising your collection class due to a specialisation of the contained objects. In fact you could just use a standard std::list<memberinfo>.

E.g.

class memberinfo
{
    bool IsLocal( ) const;
}

Then you would choose whether you’re interested in local members or not while you’re iterating through the contained objects.

E.g.

std::list<memberinfo>::iterator it;
std::list<memberinfo> list;

for ( it = list.begin() ; it != list.end() ; it++ )
{
    if ( it->IsLocal() )
    { 
        // blah blah blah
    }
    else
    {
        // dum dee dum dee
    }
}