Hello, I was reviewing the View Template Library (VTL) - see http://www.zib.de/weiser/vtl/ ... and have a few questions regarding Views as applied to STL Maps. I was also wondering if Boost was planning to eventually provide a VTL-like framework? I'm looking for a type of View that provides read-only access to an STL map, with only const iterators, but also provides limited insertion and removal access as well (as shown below): This new limited View-like map will only allow clients to iterate using const iterators, and also provides only one public insert(const key&) and one erase(const key&) method. These insert and erase member functions need to be implemented as "Template Method Functions", as follows: (see Design Patterns) * Note: these are shown using the latest SGI STL implementation (i.e., the _M_t.insert_unique and _M_t.erase calls) virtual bool preInsert(const value_type&) { return true; } pair<iterator, bool> insert(const value_type& x) { if(preInsert(x) { return _M_t.insert_unique(x); } return make_pair(end(), false); // make compiler happy } virtual bool preErase(const key_type&) { return true; } size_type erase(const key_type& x) { if(preErase(x) { return _M_t.erase(x); } return 0; // make compiler happy } The preInsert and preErase methods are virtual Hook Methods, and derived classes override these to add behavior to the (non-virtual) insert and erase functions.. Another nice addition to this map view would be a const _Tp& operator[](const key_type& k) const function, implemented something like this: const _Tp& operator[](const key_type& k) const { const_iterator i = lower_bound(k); if(i == end() || key_comp(k, (*i).first)) // if i->first is >= k throw SearchError(k); return (*i).second; } * Note: this simple implementation assumes that the key can be converted to a string in the constructor of the SearchError exception object. I have at least three Manager-like (Mediator) classes that can use this pattern (i.e., derived from this Map View class) as well as others that need a vector view with a similar filtered design... Thanks in advance, ~Matt Verona Houston, Texas USA