Question

Problem

Suppose you have a class user. You want to be able to return this user object to others so they can use it to extract information using getters. However, you don’t want people to be able to readily set the internal state because the internal information should directly relate to a row in the database. Does it make sense to have protected mutators (setters) so that only an extended class could set the variables? Is this a bad practice, irrelevant, overkill or useless?

I have considered trying to limit __construct to one use ( I believe this is sometimes refereed to as a singleton pattern – although I am not sure if I understand entirely. )

I am an amateur programer, forgive any ignorance. Thanks.

Example:

<?php

    class user
    {

    private username;

    protected function set_username($username)
    {
        $this->username = $username;
    }

    public function get_username()
    {
        return $this->username;
    }

?>

Answer 1

Depends. If nothing in particular needs to happen when the state is changed then you can leave the setters out altogether. Any subclass will have direct access to the properties that are set protected or looser.

If you need something to happen when the state changes (for example having a database UPDATE happen when the state changes) then the setters will make your life a lot easier, as the call to the database updating code be put in the setter. This means if you always go through the setter then the DB will always update when you change the object’s state.

So in short, it depends.