Trait for making protected/private attributes "gettable", leaving "setting" the attributes a matter of business logic to be implemented.

## Gettable.php
<?php

trait Gettable {

    /**
     * Retrieve private attributes.
     *   Attributes should be protected
     *   so they cannot be *set* arbitrarily.
     *   This allows us to *get* them as if they
     *   were public.
     * @param  String $key
     * @return mixed
     */
    public function __get($key)
    {
        if( property_exists($this, $key) )
        {
            return $this->$key;
        }
    }
}