# The following was supposedly scribed by
# Marvin Humphrey
# on Wednesday 29 June 2005 09:30 pm:
>SV* return_a_scalar (SV* input_sv) {
> if (return_the_input_unchanged) {
> SvREFCNT_inc(input_sv); /* otherwise it goes to zero */
> return input_sv;
> }
> else {
> SV* new_scalar = newSVpvn("foo", 3);
> return new_scalar;
> }
>}
>
>The crux of the biscuit is that Perl doesn't know that the scalar
>it's getting back is the same one it sent to C. Perl decrements the
>reference count for that scalar and cleans it up. The next time you
>try to access it, BAM! Invalid SV and segfault.
Something sounds really wrong with that. When does a perl function ever
return the same scalar that it was passed?
sub return_a_scalar {
my $s = shift;
return($s);
}
Returns a *list* with the *value* of $s as the first element.
I'm thinking sv_mortalcopy() (or maybe sv_setsv_flags()) is the way to
go here. (I use sv_2mortal() when I'm pushing to a list, you maybe
want the latter.)
Particularly if you're doing something like:
$var = return_a_scalar($var);
Perl is going to handle the refcounting here, so I don't see why you
need to mess with it. I'm pretty sure you shouldn't return(input_sv)
at all, regardless of what you do with refcounts.
--Eric
--
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