How about something like this? It's encapsulated due to lexical variables and block scope, but you have access to it with accessor methods:

package Parent;

{
    my ($name, $pass);

    sub new {
        my $class = shift;
        my $self = {};
        if (@_) {
            ($name, $pass) = @_;
        }
        @$self{'name', 'pass'} = ($name, $pass);
        bless($self, $class);
    }
}
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You could add another method in there to reset the name and password. You could store references to $name and $pass in the hash, so updating the parent data is reflected in the children.