Bài giảng Phát triển ứng dụng Web (GV Nguyễn Hữu Thể) Bài 5

Visibility public, private, protected... Properties & Methodsclass Person { private $name ; //public, protected private $age ; echo $this->name... Getter & Setterclass Person { private $

OBJECT ORIENTED PROGRAMMING

PHÁT TRIỂN ỨNG DỤNG WEB

1 Class

2 Visibility

3 Properties & Methods

4 Getter & Setter

Visibility (public, private, protected)

Properties & Methods

class Person

{

private $name ; //public, protected

private $age ;

echo $this->name " is " $this->age " years old!";

}

}

Create objects

(Create a new instance of the class)

− For example:

$person = new PerSon();

$person2 = new PerSon();

6

Getter & Setter

class Person

{

private $name ;

private $age ;

public function getName(){

return $this-> name ;

}

public function setName($name){

$this-> name = $name;

}

public function getAge(){

return $this-> age ;

}

public function setAge($age){

class Person

{

private String name ;

private int age ;

public String getName(){

return name ;

}

public void setName(String name ){

this name = name ;

class Person {

private $name ;

private $age ;

public function getName(){

return $this-> name ; }

public function setName($name){

$this-> name = $name;

}

public function getAge(){

return $this-> age ; }

public function setAge($age){

$this-> age = $age;

}

public function show(){

echo $this-> name " is " $this-> age " years old!" ; }

$p->setName( "Nguyễn Văn A" );

$p->setAge(18);

echo $p->getName() " is " $p->getAge() " years old." ;

//echo " {$p->getName()} is {$p->getAge()} years old." ;

$p->show();

Ex: Person.php

get() method

10

class GetName {

public $type = 'chocolate' ;

public $choctype = array (

'milk' => 0, 'dark' => 1, 'plain' => 2 );

public function wrap() {

echo 'Its a wrap';

}

public function get($index) {

echo '$choctype property with index of: ' $index '<br />';

return $this->choctype [$index];

}

}

$candy = new GetName ();

// set a non existant property

echo 'Value of property is: ' $candy->milk; $choctype property with index of: milk

Value of property is: 0

$this-> name = $name;

$this-> age = $age;

}

}

}

$p = new Person( "Nguyễn Trần Lê" , 18);

$p->show();

public function destruct() {

echo "Bye bye!" ;

//

}

$p = new Person( "Nguyễn Trần Lê" , 18);

14

class ParentClass {

// Method code here

}

}

class ChildClass extends ParentClass {

// For ChildClass objects, this method is called // instead of the parent class's MyMethod()

}

}

Calling a parent method from a child method

parent ::myMethod();

parent::show();

parent:: construct();

Example:

public function construct($name, $age, $salary){

parent:: construct($name, $age); // Call construct() parent

$this-> salary = $salary;

}

public function getSalary(){

return $this-> $salary;

public function display(){

echo " Name: " $this->getName() "<br>" ;

echo " Age: " $this->getAge() "<br>" ;

echo "Salary: " $this-> salary ; }

Visibility (Example 1)

Property Visibility

class MyClass {

public $public = 'Public' ;

protected $protected = 'Protected' ;

private $private = 'Private' ;

function printHello () {

echo $this -> public ;

echo $this -> protected ;

echo $this -> private ;

}

}

$obj = new MyClass ();

echo $obj -> public ; // Works

echo $obj -> protected ; // Fatal Error

Visibility (Example 2)

Property Visibility

18

class MyClass2 extends MyClass {

// We can redeclare the public and protected method, but not private

public $public = 'Public2' ;

protected $protected = 'Protected2' ;

function printHello () {

echo $this -> public ;

echo $this -> protected ;

echo $this -> private ;

}

}

$obj2 = new MyClass2 ();

echo $obj2 -> public ; // Works

echo $obj2 -> protected ; // Fatal Error

echo $obj2 -> private ; // Undefined

$obj2 -> printHello (); // Shows Public2, Protected2, Undefined

Visibility (Example 3)

Method Visibility

class MyClass {

// Declare a public constructor

public function construct () { }

// Declare a public method

public function MyPublic () { }

// Declare a protected method

protected function MyProtected () { }

// Declare a private method

private function MyPrivate () { }

$myclass2 = new MyClass2 ;

$myclass2 -> MyPublic (); // Works

$myclass2 -> Foo2 (); // Public and Protected work, not Private

private function testPrivate () { echo "Foo::testPrivate\n" ; }

}

$myFoo = new Foo ();

$myFoo -> test (); // Bar::testPrivate

// Foo::testPublic

Abstract class

− An abstract class is a class that cannot be instantiated on its

own

22

abstract class Mathematics {

/*** child class must define these methods ***/

abstract protected function getMessage();

abstract protected function add($num);

Abstract class

require_once 'Mathematics.php' ;

class myMath extends Mathematics {

return "The anwser is: " ;

// A new instance of myMath

$myMath = new MyMath ();

$myMath->showMessage ();

− An interface declares one or more methods.

− Must be implemented by any class that implements the

interface.

24

interface MyInterface {

public function aMethod();

public function anotherMethod();

}

class MyClass implements MyInterface {

public function aMethod() {

// (code to implement the method)

}

public function anotherMethod() {

// (code to implement the method)

} }

interface Persistable {

public function save();

public function load();

public function delete();

$this-> username = $username;

$this-> location = $location;

$this-> homepage = $homepage;

}

public function getUsername() {

return $this-> username ;

}

public function getLocation() {

return $this-> location ;

}

public function save() {

echo "Saving member to database<br>" ;

}

public function load() {

echo "Loading member from database<br>" ;

}

public function delete () {

echo "Deleting member from database<br>" ;

} }

$m = new Member ( "Aha" , "VN" , "No page" );

echo $m->getUsername() "<br>" ;

$m->load();

class Topic implements Persistable {

private $subject ;

private $author ;

private $createdTime ;

public function construct( $subject, $author ) {

$this-> subject = $subject;

$this-> author = $author;

$this-> createdTime= time();

}

public function showHeader() {

$createdTimeString = date( 'l jS M Y h:i:s A' , $this-> createdTime );

$authorName = $this-> author ->getUsername();

echo " $this-> subject (created on $createdTimeString by $authorName )<br>" ; }

public function save() {

echo "Saving topic to database<br>" ; }

public function load() {

echo "Loading topic from database<br>" ; }

public function delete () {

echo "Deleting topic from database<br>" ; }

}

require_once 'Member.php' ;

require_once 'Topic.php' ;

$aMember = new Member ( "TUI" , "Viet Nam" , "http://example.com" );

echo $aMember->getUsername () " lives in " $aMember->getLocation () "<br>" ;

$aMember->save ();

$aTopic = new Topic ( "PHP is Great" , $aMember );

$aTopic->showHeader ();

$aTopic->save ();

TUI lives in Viet Nam

Saving member to database

PHP is Great (created on Saturday 17th Dec 2016 03:00:07 AM by TUI)

Saving topic to database

Test.php

$member = new Member ("TUI", "Viet Nam", "No page");

echo "Created object: ";

print_r ( $member );

Loaded Member.php

Created object: Member Object ( [username:Member:private] => TUI

[location:Member:private] => Viet Nam [homepage:Member:private] => No page )

Anonymous functions

− Anonymous functions have no name

// Assign an anonymous function to a variable

$makeGreeting = function ($name, $timeOfDay) {

return ( 'Good ' $timeOfDay ', ' $name);

};

// Call the anonymous function

echo $makeGreeting ( 'Tom' , 'morning' ) '' ;

echo $makeGreeting ( 'Jerry' , 'afternoon' ) '' ;

Good morning, Tom

Good afternoon, Jerry

− A closure is an anonymous function that can access variables

imported from the outside scope without using any global

− Namespaced code is defined using a singlenamespace

keyword at the top of your PHP file

− It must be the first command (with the exception ofdeclare)

and no non-PHP code, HTML, or white-space

// define this code in the 'MyProject' namespace

namespace MyProject;

// code

namespace test;

include 'Cat.php' ;

include 'Dog.php' ;

include 'Animal.php' ;

use foo as cat;

use bar as dog;