...but, of course (5 years later), it is easy to make this work well under mod_perl:

BEGIN {
    my $cmpval= sub {
        my( $val1, $val2 )= @_;
        if(  ref($val1) eq 'Node'  ) {  $val1= $val1->{node_id};  }
        if(  ref($val2) eq 'Node'  ) {  $val2= $val2->{node_id};  }
        return $val1 eq $val2;
    };

    sub getWorkspace {
        # ...
        $match= 0  if  ! $cmpval->( $N->{$_}, $WHERE->{$_} );
        # ...
    }
}
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