[Boost-users] how to release element from ptr_map?

I have an instance of ptr_map. I need to release an element from the map and use it somewhere else, making sure that it will not be deleted when the instance of ptr_map is deleted. I am successfully doing it with ptr_vectors, but can't get it right with ptr_map. What is the proper syntax of such call? I am doing it like in the code below, which does not compile. class classA {}; typedef ptr_map ptrmaptype; ptrmaptype val; val.insert(1, new classA()); ptrmaptype::mapped_type t = val.release (val.begin()); // I want "t" to be of classA* type