C-Interface (Memory Management)

[Peter Herkenrath]

Hi folks,
as an old Perl addict I missed pattern matching in Mercury. 
I wanted to reuse an Sicstus interface to the regex library (prolog-rx
by Gerd van Noord).
The C function regex_match should return the matched substrings as a
list(string) type. Such a case is not mentioned in the Language
Reference
and not demonstrated in samples/c_interface.
After much try and error I finally managed to make a (mostly) working
interface to the regex library. The strings were allocated via
make_many(), 4cons4ed by an Mercury function, ... .
The general questions:
Is this the 4right4 way to allocate memory for an object which will be
used by Mercury?
When (and how) should such Objects be deallocated (via oldmem?)?

many thanks

Peter Herkenrath