Swig and Memory Leaks

Hello,

Anybody with experience with Swig?
Does it usually takes care on freeing unused variables?

Packages generated by Swig include a DESTROY method:

 >  sub DESTROY {
 >    return unless $_[0]->isa('HASH');
 >    my $self = tied(%{$_[0]});
 >    return unless defined $self;
 >    delete $ITERATORS{$self};
 >    if (exists $OWNER{$self}) {
 >        Lingua::FreeLing3::Bindingsc::delete_word($self);
 >        delete $OWNER{$self};
 >    }
 > }

But I am not able to understand this completely.
I can say that the detele_word(...) method exists, and that it seems to 
delete the used memory.
But not easy to understand if/when it is called.

Thanks for any hint/pointer

Cheers
ambs