PHP OOP Example - Showing namespaces, abstract classes, visibility, and inheritance

A Note

PHP OOP Example
===============

Showing the use of classes and how they can be related using inheritance.

$person = new Person();

Abstract classes can not be instantiated

Output:
Fatal Error
===========


$teacher = new Teacher();
$teacher->personalnumber = "1234";
print($teacher->getPersonalNumber());

Output: 
13T1234
=======


$student = new Student();
$student->personalnumber = "9384";
print($student->getPersonalNumber());

Output: 
13S9384
=======


If the student is already expelled returns false, otherwise expelling
a student returns the $student so that more methods can be performed
on the student object:
e.g getParentDetails(), sendParentLetter()

$student = new Student();
$expelledstudent = $student->expell();
$expellexpelledstudent = $expelledstudent->expell();

var_dump($expelledstudent);
var_dump($expellexpelledstudent);

Output:
object(rowleyaj\phpexample\Student)#1 (6) {
  ["personalnumberformat":protected]=>
  string(5) "13S%s"
  ["expelled":"rowleyaj\phpexample\Student":private]=>
  bool(true)
  ["name"]=>
  NULL
  ["dateofbirth"]=>
  NULL
  ["gender"]=>
  NULL
  ["personalnumber"]=>
  NULL
}
bool(false)

BaseModel.php

<?php
namespace rowleyaj\phpexample;

abstract class BaseModel
{
    // BaseModel created to allow shared methods to be added to 
    // objects without editing each individually

    /**
     * Prevent overloading of new properties
     * @param  string $name
     * @return false
     */
    public function __get($name)
    {
        return null;
    }

    /**
     * Prevent overloading of new properties
     * @param [type] $name  [description]
     * @param [type] $value [description]
     */
    public function __set($name, $value)
    {
        return null;
    }
}

Person.php

<?php
namespace rowleyaj\phpexample;

abstract class Person extends BaseModel
{
    public $name;
    public $dateofbirth;
    public $gender;
    public $personalnumber;
    /**
     * Format string for sprintf
     * @var string
     */
    protected $personalnumberformat = '%s';

    /**
     * Get formatted personal number ready for printing
     * @return string
     */
    public function getPersonalNumber()
    {
        // Assign vars only for readability
        $number = $this->personalnumber;
        $format = $this->personalnumberformat;
        return sprintf($format, $number);    
    }
}

Student.php

<?php
namespace rowleyaj\phpexample;

class Student extends Person
{
    /**
     * Format string for sprintf
     * @var string
     */
    protected $personalnumberformat = '13S%s';

    /**
     * Represents if student is expelled. Can not be undone.
     * @var bool
     */
    private $expelled = false;

    /**
     * Expell a student
     * Expelling a student requires additional processing and callbacks
     * so can not be set directly. e.g. Sending letter to parents
     * 
     * If already expelled return false to prevent callbacks 
     * and additional processing
     * @return Student or bool
     */
    public function expell()
    {
        if ($this->expelled) {
            return false;
        }

        $this->expelled = true;

        return $this; // Allows chaining
    }
}

Teacher.php

<?php
namespace rowleyaj\phpexample;

class Teacher extends Person
{
    /**
     * Format string for sprintf
     * @var string
     */
    protected $personalnumberformat = '13T%s';
    
    /**
     * Line Manager - Teacher or false
     * @var Teacher or Bool
     */
    public $linemanager = false;
}