Indexing of Groups

Both the GroupOf class as well as the CollectionOf class assign a unique group relative rank to each group member such that group members can be addressed by their rank.

GroupOf<FlockMember> group(...);

int kg;
for(int i=0; i < group.size(); i++)
    kg = group[i].invoke( m2f(&Sheep::feed, 18) );

Therefore we can easily access each group member individually.