my $f = Foo->new(); # normal creation
print ref $f;       # prints "Foo"
print $f;           # prints "Foo=HASH(0x19a0ef8)"

my $aref = $f->getVariants(); # reference to array containing many Foo
+s
print ref $aref->[0];         # prints "Foo"
print $aref->[0];             # prints "Foo=SCALAR(0x19c8290)"
[download]

Not surprisingly, calling ACQUIRE with one of the SCALARS gives the error "Not a HASH reference at..." when it tries to call tied, since the ACQUIRE method generated by SWIG assumes a HASH. Here's the SWIG-generated Perl for class Foo:

package Bar::Foo;
use vars qw(@ISA %OWNER %ITERATORS %BLESSEDMEMBERS);
@ISA = qw( Bar );
%OWNER = ();
%ITERATORS = ();
sub new {
    my $pkg = shift;
    my $self = Barc::new_Foo(@_);
    bless $self, $pkg if defined($self);
}

sub DESTROY {
    return unless $_[0]->isa('HASH');
    my $self = tied(%{$_[0]});
    return unless defined $self;
    delete $ITERATORS{$self};
    if (exists $OWNER{$self}) {
        Barc::delete_Foo($self);
        delete $OWNER{$self};
    }
}

*AllVariants = *Barc::Foo_AllVariants;
sub DISOWN {
    my $self = shift;
    my $ptr = tied(%$self);
    delete $OWNER{$ptr};
}

sub ACQUIRE {
    my $self = shift;
    my $ptr = tied(%$self);
    $OWNER{$ptr} = 1;
}
[download]

For reference, here are the lines from the SWIG-generated C++ wrapper that appear to create the Foo objects.

The first line appears in the wrapper for the new method. The second line is from the wrapper for the method returning the array of objects:

SWIG_NewPointerObj(SWIG_as_voidptr(result), SWIGTYPE_p_Foo, SWIG_OWNER
+ | SWIG_SHADOW)

SWIG_NewPointerObj(x, SWIGTYPE_p_Foo, 0)
[download]

I could make a Perl-specific helper class in C++ with a getNext method which could then be used by a Perl method in the wrapper, like so:

%perlcode %{

sub getAllVariants
{
    my ($self) = @_;
    my $fv = FooVariants->new($self);
    my $aref = [];

    while ( my $foo = $fv->getNext() )
    {
    $foo->ACQUIRE();    # C++ code does not delete this, so ensure del
+ete_ method is called
    push( @$aref, $foo );
    }

    return $aref;
}
%}
[download]

I know this technique works, but I'd prefer an all-Perl method. Is there a way to change a SCALAR into a HASH using just Perl without any XS or C++ code?