Re: Checking for undefined in Perl interface code?

man perlguts:       If you want to know if this variable (or any other SV) is       actually defined, you can call:
           SvOK(SV*)
       The scalar undef value is stored in an SV instance called       PL_sv_undef.  Its address can be used whenever
anSV* is       needed.
 

May be:
if (! (SvOK(perlret) && perlret != &PL_sv_undef) ) {...


Tom Lane wrote:

> PL/Perl tries to handle an "undef" result from a Perl function (which
> should convert to a SQL NULL) with code like so:
> 
>     /* XXX is this the approved way to check for an undef result? */
>     if (perlret == &PL_sv_undef)
>     {
>         retval = (Datum) 0;
>         fcinfo->isnull = true;
>     }
>     else
>     {
>     // handle non-null result
>     }
> 
> But I find that it doesn't work, at least not on RH Linux 7.2 with
> perl 5.6.0.  The if-test fails to notice undef results.
> 
> Anyone know what the correct way to do this is?
> 
>             regards, tom lane
> 
> ---------------------------(end of broadcast)---------------------------
> TIP 4: Don't 'kill -9' the postmaster
> 
> 


-- 
Teodor Sigaev
teodor@stack.net