...
my $offset;
BEGIN {
    $offset= 0; # Or BaseClass->_GetMaxOffset();
    for my $attrib (  qw/ foo bar baz /  ) {
        eval "sub _$attrib() { $offset }; 1"
            or  die $@;
        $offset++;
    }
}
sub _GetMaxOffset { $offset }

# Example method
sub Foo {
    my $me= shift @_;
    my $old= $me->[_foo];
    if(  @_  ) {
        my $new= shift @_;
        # validate here
        $me->[_foo]= $new;
    }
    return $old;
}