Variable number of arguments in C language function.

Hi,

Under PostgreSQL 7.1.3, I'm attempting to create a 'C' language
function using the V1 style interface which accepts a variable
number of parameters.  That part appears to work fine, in that
I can retrieve the number of arguments from the fcinfo structure
passed into the C function, and am able to extract the appropriate
argument.

What I'm attempting to do is, and coming unstuck at, is to "CREATE
FUNCTION" that allows a variable number of arguments to be passed
in, without having to define a seperate function in pg_proc for
each argument count.  There is a comment in the FmgrInfo structure
in include/fmgr.h about fn_nargs stating "or -1 if variable arg",
but setting pronargs to -1 for the appropriate pg_proc entry just
resulted in "Function pg_exec(unknown) does not exist".

My goal was to be able to pass in arguments of any type into the
function and have it handle (and convert) the argument type, but
(and this brainwave only occurred in the last five minutes) I
suspect that I may not be able to extract the data type from Datum,
and that's the reason why this typing mechanism for pg_proc exists
in the first place.  The ultimate aim is to create a "pg_exec"
function that will allow passing in of ints, floats and strings
and execve them as arguments, with the non-string arguments being
converted to string equivalents.  Is this achievable, or am I
barking up the wrong forest?  Thanks in advance.

--
Regards,
  Daryl Tester,  Software Wrangler and Bit Herder, IOCANE Pty. Ltd.