I once wrote an interface to a low-level API accessing a database. The point was to simplify the access to data by hiding many of the gory details of the low level API. One of the things I did in my interface module was to store in closures most of the information I did not want the module user (usually me) to have to care about (connection ID, transaction ID, error buffer ID, etc.). The user would just need to call an init function at the beginning of the program and then simply call the functions to query the data, the module taking care of the underlying details. I do not know if this applies to your case, but I was quite happy with this solution which made our lives much easier.