I definitely think this would be useful, but more in the line of a general utility that allows me to create an input iterator that's based on a function object. Something like boost::make_function_output_iterator(...) only boost::make_function_input_iterator(...).
I'm guessing, you might have a generic function that returns an iterator from a container. You might argue that it would be good to wrap your container in such a way that you have:
std::list<std::string> cities; // contain the list of cities currently_unnamed_wrapper<unsigned int, std::list<std::string> > city_finder(cities); std::list<std::string>::iterator city_iterator = city_finder[zip_code]; std::cout << *city_iterator << std::endl;
Is this similar to what you've already implemented?
Not at all at this point. For simplicity, I defined an 'Indexer' concept, which implements the following functions: int lookup( const T& key ) const; size_t size() const; (plus some other callback type stuff to be discussed later) These are passed to the 'LookupTable' class as template arguments, using a trick similar to the 'tuple' class, and currently supporting up to 10 dimensions. The generated object then looks and feels like a multi_array, but extended with 'operator()' which does lookups based on key, rather than index. So, access to a two dimensional array with the first dimension indexed using strings and the second using doubles would be like: a("string")(1.0) I made the 'indexers' accessible through the LookupTable object through a templated 'indexer<>' function. Since the indexers define the shape of the array, it only makes sense that the shape be changed through them. Thus, there's a callback mechanism (through friendly base classes) that allows the indexer to inform the underlying array of any shape changes (ie: remove indices n..n+k from dimension m, ...) The whole function output iterator seems maybe 'too external', in that it doesn't create a tight connection between the container indexing a dimension and the underlying multi array; how to keep them in sync? Chris