Re^3: C++ object & PERL garbage collection

if done in a routine and returned to MAIN; it dumps core

So the following would dump core:

my $dsgn = create_new();
$dsgn->(method);

sub create_new {
    my $ret = new (c++_object);
    return $ret;
}
[download]

I wonder what would happen if the reference count were incremented before returning:

my $dsgn = create_new();
$dsgn->(method);

sub create_new {
    my $ret = new (c++_object);
    refcnt_inc($ret);
    return $ret;
}
[download]

I don't think there exists a perl function/module that implements a reference count increment - in which case you'd need to do it with Inline::C/XS/SWIG. (I guess SWIG can help out there ... I know nothing about it.) Even if incrementing the reference count does work, that doesn't guarantee that it's the most appropriate thing to do.

A simple little Inline::C script that increments the reference count:

use warnings;
use Inline C => Config =>
    BUILD_NOISY => 1;

use Inline C => <<'EOC';

void refcnt_inc(SV * sv) {
     SvREFCNT_inc(sv);
}

SV * get_refcnt(SV * sv) {
    return newSVuv(SvREFCNT(sv));
}

EOC

$x = 1;
print get_refcnt($x), "\n";
refcnt_inc($x);
print get_refcnt($x), "\n";
[download]

Not sure if there's anything in this post that helps .... :-)

Cheers,
Rob

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Re^4: C++ object & PERL garbage collection by Anonymous Monk on Sep 23, 2006 at 02:28 UTC
yes, your code snippet dumps core `my $dsgn = subA(); $dsgn->method(); sub subA { my $obj = new (c++_object); return $obj; }` [download] however, a "minor" change to the code works `my $obj = new (c++_object) subA($obj) sub subA { my ($object) = @_; $object->method(); }` [download] that's what i mean about up & down in other posts. in other words `CALLEE can NOT return OBJECT CALLER can ALWAYS pass OBJECT` [download] and the C++ folks say that it is PERL deleting the object because it is no longer in scope.	[reply] [d/l] [select]
Re^4: C++ object & PERL garbage collection by diotalevi (Canon) on Sep 23, 2006 at 03:05 UTC
There are functions to increment the reference count of a SV but they're not relevant here. ⠤⠤ ⠙⠊⠕⠞⠁⠇⠑⠧⠊	[reply]