Kofi Ramos Amoussou

What is OOP?

OOP is a coding methodology and style
it makes it easy to extend and reuse our code
easier to maintain and debug when things go wrong

Blocks of OOP

Classes, properties & methods
Access modifiers(private, public, static), getters & setters
Inheritance, static properties & magic methods

Classes

they are blueprints for objects. So this contains properties(variables) and methods(functions) of an object.

Creating a class

There are a few conventions to follow when creating a class

First letter Capital
Singular Name

// creating a user clas
class User {

}

// Instantiating a new user and creating a use object
$userOne = new User();
$userTwo = new User();

Properties and Methods

Properties

They are like variables for classes

class User {

	// public makes it for these properties to be accessed by the object later
	public $username = 'ramos';
	public $email = 'karsoft92@gmail.com'; 

}

$userOne = new User();

//accessing the properties above

echo $userOne->username

Methods

These are functions

class User {

	// public makes it for these properties to be accessed by the object later
	public $username = 'ramos';
	public $email = 'karsoft92@gmail.com'; 


	public function addFriend(){
		// this refers to the instance on which the method is being called on
		// $this->username;
		return "$this->username added a new friend";
	}

}


// calling a method of the User class
echo $userOne->addFriend();

// shows different properties in class
print_r(get_class_vars('User'));

// shows different methods available in that class
print_r(get_class_methods());

Setting

we can set the properties to another value we desire

// 
$userOne->username="kofi";
$userOne->email="karsoft93@gmail.com"

Constructors

Use a constructor function to run the moment we instantiate a class

class User {

	// public makes it for these properties to be accessed by the object later
	public $username;
	public $email;
	//constructor function to make class able to access parameters

	public function __construct($username, $email){
		$this->username= $usename;
		$this->email= $email;
	}


	public function addFriend(){
		// this refers to the instance on which the method is being called on
		// $this->username;
		return "$this->username added a new friend";
	}

}


// instatiating and filling object with parameters
echo $userOne = new User('kofiramos','kofiramos87@fmail.com');

Access Modifiers

Access Modifiers defines the access scopes of methods and properties of a class.

public makes properties and methods accessible inside and outside the class
private makes properties and methods accessible only inside the class but not outside the class

Getters and Setters

Getters

creating getters to be able to access private properties

class User {

 	public $username;
	private $email; // private property
	//constructor function to make class able to access parameters

	public function __construct($username, $email){
		$this->username= $usename;
		$this->email= $email;
	}

	//getter for email

	public function getEmail(){
		return $this->email;
	}


	public function addFriend(){
		// this refers to the instance on which the method is being called on
		// $this->username;
		return "$this->username added a new friend";
	}

}


// echoing the the email through the method
echo $userOne->getEmail();

Setters

Updating private property with setters

class User {

 	public $username;
	private $email; // private property
	//constructor function to make class able to access parameters

	public function __construct($username, $email){
		$this->username= $usename;
		$this->email= $email;
	}

	//getter for email

	public function getEmail(){
		return $this->email;
	}

	//setter 

	public function setEmail($email){
		//checking if @ exists in the string to confirm it's an email
		if(strpos($mail,'@') > -1):
			$this->email = $email;
		endif;
	}


	public function addFriend(){
		// this refers to the instance on which the method is being called on
		// $this->username;
		return "$this->username added a new friend";
	}

	public function message(){
		return "$this->email person sent a message";
	}

}


// echoing the the email through the method
echo $userOne->getEmail();

//setting email
$userOne->setEmail('kar@zmail.com');

Inherintance

It’s when one calss inherits properties & methods from another class

class AdminUser extends User{

	public $level;
	public function __construct($username,$email,$level){
		$this->level = $level;

		// this is to get access and inherit User class properties
		parent::__contstruct($username,$eimail);
	}
	
}

// instantiating a AdminUser object

$userThree = new AdminUser('Ramos','Kofiramos9238@zmail.com',5);

Overriding properties and methods

class AdminUser extends User{

	public $level;
	public $role="admin"; // overriding parent properties


	public function __construct($username,$email,$level){
		$this->level = $level;

		// this is to get access and inherit User class properties
		parent::__contstruct($username,$eimail);
	}

	// can't be accessed because it's a private property
	public function message(){
		return "$this->email, an admin, sent a message;"
	}
	
}

Dealing with protected properties

Protected properties behave as private but they can be used between classes but not outside the classes.

class User{
	protected $email;
}

class AdminUser extends User{

	public $level;
	public $role="admin"; // overriding parent properties


	public function __construct($username,$email,$level){
		$this->level = $level;

		// this is to get access and inherit User class properties
		parent::__contstruct($username,$eimail);
	}

	public function message(){
		return "$this->email, an admin, sent a message;"
	}
	
}

Magic methods

__contstruct, __distruct and __clone

Distruct method

This removes any instance references after all methods have been executed

class AdminUser extends User{

	public $level;
	public $role="admin"; // overriding parent properties


	public function __construct($username,$email,$level){
		$this->level = $level;

		// this is to get access and inherit User class properties
		parent::__contstruct($username,$eimail);
	}

	public function __destruct(){
		echo "the user $this->username was removed"
	}

	public function message(){
		return "$this->email, an admin, sent a message;"
	}
	
}

Clone method

this is used to clone methods and properties

class AdminUser extends User{

	public $level;
	public $role="admin"; // overriding parent properties


	public function __construct($username,$email,$level){
		$this->level = $level;

		// this is to get access and inherit User class properties
		parent::__contstruct($username,$eimail);
	}

	public function __destruct(){
		echo "the user $this->username was removed"
	}

	public function __clone(){
		$this->email = $his->email. '(cloned)';
	}

	public function message(){
		return "$this->email, an admin, sent a message;"
	}
	
}
$userFour = clone $userOne;

Static Properties and Methods

They are accessed directly from the class and not an instance.

 
 class Weather {

 	public static $conditions = ['cold','mild','warm'];

 	// converts from celsius to farenheit
 	public static function celsiusToFarenheit($c){

 		return $c * 9 / 5 + 32;
 	}

 	public static function determineTempCondition($f){
 		if($f < 40){
 			return self::$condition[0]; // self is the equivalent of $this in static properties and methods
 		}else if ($f < 70){
 			return self::$condition[1];
 		}else{
 			return self::$condition[2];
 		}
 	}

 }

//accessing static properties
 print_r(weather::$conditions);

// accessing static method
echo Weather::celsiusToFarenheit(20);

OOP PHP

Feb 3, 2021