DLM returning a pointer...

[Randall Skelton <rhskelto(at)atm.ox.ac.uk>]

Hi all,

I am trying to write a few IDL functions which mirror those of a C library
I frequently use for getting data directly from a unix database
connection.  My problem is that the interface document states that the
internal C structures should not be directly used; rather, an additional
layer of abstraction should be used.  The basic operation that I want in
IDL is the ability to (1) connect to the database, (2) give a string of
queries, (3) get a stream of data, and (4) close the connection.  
Ideally, I would like each of these steps to be a separate IDL function
that mirrors the C functions.  Implementing step 1 is proving to be
somewhat difficult with the abstraction requirement. In order to establish
a connection I use a C function:

DBcon *DBconSet(char *host, char *port, char *dbName, ...)

which returns DBconn (a nasty structure that, for the reasons above, I
don't want to emulate directly in IDL). Nevertheless, this structure is
passed in subsequent functions so I need the structure to proceed with
steps 2, 3, and 4.

DBresult *DBexecute(DBconn *connection, const char *query)
char *DBgetval(DBconn *connection, int tup, int index)

Is it possible to return a pointer from C -> IDL such that I can pass a
pointer of the DBcon memory block in subsequent functions from IDL -> C?

Does anyone have any code that shows how to do this?

Thanks in advance,
Randall