package My::Inner;

# Usage:  use My::Inner qw< _wrap _unwrap _incRefs _decRefs >;
# Defines the using class as an inner class wrapped by some other class
# (the wrapping class must use My::Outer).
# The using class must define the following methods:
#     _new:   the constructor
#     _free:  breaks ref cycles if all related inner objects are unref'd
#+    _incRefs: increments inner object's ref count
#+    _decRefs: decrements inner object's ref count, returning result
#+ If using class creates blessed hashes and wants $obj->{refs} to be the ref
#+ count, then it can just import the _incRefs and _decRefs methods.
##  (Not: "Using class must create blessed hashes so $obj->{ref},
##  $obj->{wrapper} work.")

use Exporter 'import';
BEGIN { our @EXPORT_OK= qw< _wrap _unwrap _incRefs _decRefs >; }

sub _wrap {
    my( $in, $class )= @_;
    my $out= bless \$in, $class;
    $in->_incRefs();
    ##  if(  $class  ) {
    ##      $in->{wrapper}= $class
    ##  } else {
    ##      $class= $in->{wrapper};
    ##  }
    return $out;
}

sub _unwrap {
    my( $in )= @_;
    if(  ! $in->_decRefs()  ) {
        $in->_free();
    }
}

#+ (Added below code)
sub _incRefs {
    my( $in )= @_;
    $in->{refs}++;
}

sub _decRefs {
    my( $in )= @_;
    return --$in->{refs};
}