Re: [HACKERS] Re: Bugs: Programming Language Functions

On Tue, 11 Apr 2000, Tom Lane wrote:
> "Andrew C.R. Martin" <a(dot)c(dot)r(dot)martin(at)reading(dot)ac(dot)uk> writes:
> > My own particular problem simply pulls out an integer and a (text *)
> > from a varchar. It then goes away and does some calculations based on
> > these values and another external file (in fact it does a system() to
> > run an external program which does these calculations). It then build
> > a 'text' structure containing the result.
>
> Hm. I'm not too clear on why that would need to worry about either
> TupleTableSlot or GetAttributeByName ... shouldn't it be a simple
> function consuming a text Datum and producing another?

Errrmmm, just following the instructions in the docs:

Programmer's Manual, Chapter 4. Extensing SQL: Functins (page x414.htm), under
the C examples.

My function looks something like:

text *mppfunc(TUPLE tuple)
{
text *attrib;
int resnum;
bool isnull;
char my_result[400];

if(((attrib = (text *)GetAttributeByName(tuple, "substitution", &isnull))
==NULL) || isnull)
return(pg_text("Invalid1"));
strncpy(newres, VARDATA(attrib), 40);

resnum = (int)GetAttributeByName(tuple, "codon", &isnull);
if(isnull)
return(pg_text("Invalid3"));

/* Do some stuff here putting a result string in my_result */
return(pg_text(my_result));

}

pg_text() is a little function to put a string into a PostgreSQL text data type.

Are you suggesting there is now an undocumented(?) easier way of doing this???

Best wishes,

Andrew

--
Dr. Andrew C.R. Martin EMail: a(dot)c(dot)r(dot)martin(at)reading(dot)ac(dot)uk (work)
Lecturer in Bioinformatics andrew(at)stagleys(dot)demon(dot)co(dot)uk (home)
University of Reading
Tel.: +44 (0)118 987 5123x7022 Fax: +44 (0)118 931 0180