Rwilding <[EMAIL PROTECTED]> writes:
>Hi,
>
>I hope this post is in the right place, I couldn't find an embedded perl
>list but my question is also related to xs. If anyone knows a more
>appropriate list could they please let me know? Thanks.
>
>I'm embedding PERL into my C++ app to act as a scripting interface for
>users. callbacks to the internal C/C++ routines are via XS. In some cases I
>also use the PERL instance to evaluate expressions entered by the user and
>this is where i'm experiencing a problem:
>
>As per the perlcall docs I generate a pointer to an anonymous sub routine
>using
>
> 'SV *cvrv = eval_pv("......",TRUE)'
>
>Then mess with the stack before "call_sv(cvrv,G_ARRAY)" and then more
>messing with the stack to get the result.
>
>This all works fine until the user enters an invalid expression which i then
>attempt to compile. I couldn't find any docs describing how to handle this
>but I've found (through playing with the debugger) that "cvrv->sv_any" will
>be NULL if the compilation fails.
>Firstly is this the best (only?) way to
>extract success/fail info (it's undocumented and therefore i dont want my
>code to break with an updates etc) and secondly how can i return the useful
>compilation error message from the PERL interpreter? (i.e. "Scalar found
>where.....")
It it not the best or only way.
The best way is to realise that the eval_pv is doing the save as perl's
eval ""; You can test for success by doing the C equivalent of perl's
if ($@) { print $@; }
$@ is tested commonly enough in the core for there to be a handy
C macro for it: ERRSV so you get what you want with:
if (SvTRUE(ERRSV))
{
char *error_message = SvPV_nolen(ERRSV);
}
>
>I've looked through perlguts, perlapi and perlcall - any other ideas????
>
ERRSV is meantioned in perlcall.pod and perlembed.pod as the equivalent
of testing $@ - perhaps what is not clear is that eval_pv() is like eval "".
--
Nick Ing-Simmons
http://www.ni-s.u-net.com/
