Question

I am wondering what visibility would give best practises on using data mapping pattern?

private/public/protected

When protected I would need to use the getters() in my save() method on the mapper class.

If private and public I would be able to do $user->id; in the mapper class. What does make most sense?

Answer 1

In my opinion and I often use it this way, properties are protected and my class uses magic methods for getters and setters. The way I do it you are able to do both. The best thing I like about using setter-methods is using fluent interfaces.

/**
 * Handling non existing getters and setters
 *
 * @param string $name
 * @param array $arguments
 * @throws Exception
 */
public function __call($name, $arguments)
{
    $type = substr($name, 0, 3);

    // Check if this is a getter or setter
    if (in_array($type, array('get', 'set'))) {
        $property = lcfirst(substr($name, 3));

        // Only if the property exists we can go on
        if (property_exists($this, $property)) {
            switch ($type) {
                case 'get':
                    return $this->$property;
                    break;

                case 'set':
                    $this->$property = $arguments[0];
                    return $this;
                    break;
            }
        } else {
            throw new \Exception('Unknown property "' . $property . '"');
        }
    } else {
        throw new Exception('Unknown method "' . $name . '"');
    }
}

/**
 * Magic Method for getters
 *
 * @param string $name
 * @return mixed
 */
public function __get($name)
{
    $method = 'get' . ucfirst($name);
    return $this->$method();
}

/**
 * Magic Method for setters
 *
 * @param string $name
 * @param mixed $value
 */
public function __set($name, $value)
{
    $method = 'set' . ucfirst($name);
    return $this->$method($value);
}

Using fluent interfaces looks like this:

$post->setTitle('New Post')
     ->setBody('This is my answer on stackoverflow.com');

Some thoughts on the single possibilities:

Private

Using private properties prevents me from extending my model classes and reusing some functionality.

Public

There will be no way in to intercept changes to the variables. Sometimes it is needed to do something on setting.

Protected

The best way for me. The properties are not publicly changeable and I force other developers to write getters and setters for their properties which have additional functionality. Also in my opinion this way you prevent others from making mistakes in misusing your model class.