PHÁT TRIỂN ỨNG DỤNG WEB
OBJECT ORIENTED PROGRAMMING
Nguyễn Hữu Thể
Content
1. Class 2. Visibility 3. Properties & Methods 4. Getter & Setter 5. Create objects 6. Constructor 7. Destructor Inheritance 8. 9. Abstract class 10. Interfaces 11. Autoloading classes 12. Anonymous functions 13. Closures 14. Namespace
2
Class
class ClassName {
// Properties
// Methods
}
3
Visibility (public, private, protected)
− Three levels:
• public • private • protected
− By default, all class members are public.
4
Properties & Methods
class Person {
private $name; //public, protected private $age;
public function show(){
echo $this->name . " is " . $this->age . " years old!";
}
}
5
Create objects (Create a new instance of the class)
− Using the new keyword:
new ClassName()
− For example:
$person = new PerSon(); $person2 = new PerSon();
6
Getter & Setter
JAVA
PHP
class Person {
class Person {
private String name; private int age;
private $name; private $age;
public String getName(){
return name;
public function getName(){ return $this->name;
} public void setName(String name){
} public function setName($name){
this.name = name;
$this->name = $name;
} public int getAge(){ return age;
} public function getAge(){ return $this->age;
} public void setAge(int age){
} public function setAge($age){
this.age = age;
$this->age = $age;
}
}
}
}
7
class Person{
Ex: Person.php
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!";
}
}
8
$p = new Person(); $p->setName("Nguyễn Văn A"); $p->setAge(18); echo $p->getName() . " is " . $p->getAge() . " years old."; //echo "{$p->getName()} is {$p->getAge()} years old."; $p->show();
__set() method
class SetName {
public function __set($variable, $value) {
// echo $variable; echo "My " . $variable . " is " . $value . "\n";
}
$obj = new SetName (); $obj->Name = ‘Tom'; $obj->Name = ‘Jerry';
My Name is Tom My Name is Jerry
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}
__get() method
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 . '
';
return $this->choctype [$index];
}
}
$choctype property with index of: milk 10 Value of property is: 0
$candy = new GetName (); // set a non existant property echo 'Value of property is: ' . $candy->milk;
Constructor
public function __construct() {
//...
}
public function __construct($name, $age) {
//...
}
11
Constructor
class Person{
private $name; private $age;
public function __construct($name, $age) {
$this->name = $name; $this->age = $age;
} public function show(){
echo $this->name . " is " . $this->age . " years old!";
}
}
$p = new Person("Nguyễn Trần Lê", 18); $p->show();
12
Destructor
public function __destruct() {
//...
− Example:
}
public function __destruct() {
echo "Bye bye!"; //...
}
− Using:
$p = new Person("Nguyễn Trần Lê", 18); unset( $p ); // or exit: call __destruct() object $p->show(); // Object not found
13
Inheritance
class ParentClass {
public function myMethod() {
// Method code here
}
}
class ChildClass extends ParentClass { public function myMethod() {
// For ChildClass objects, this method is called // instead of the parent class's MyMethod()
}
}
14
Calling a parent method from a child method
parent::myMethod();
Example:
parent::show(); parent::__construct();
15
require_once 'Person.php'; class Employee extends Person{
private $salary;
Inheritance
public function __construct($name, $age, $salary){
parent::__construct($name, $age); // Call __construct() parent $this->salary = $salary;
} public function getSalary(){ return $this-> $salary;
} // Override public function show(){ parent::show(); echo " Salary: " . $this->salary;
} public function display(){
echo " Name: " . $this->getName() . "
";
echo " Age: " . $this->getAge() . "
";
echo "Salary: " . $this->salary;
}
$e = new Employee("Nguyễn Lê", 20, 200); $e->show();
}
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Nguyễn Lê is 20 years old! Salary: 200
Visibility (Example 1) Property Visibility
public $public = 'Public'; protected $protected = 'Protected'; private $private = 'Private';
class MyClass {
function printHello() { echo $this->public; echo $this->protected; echo $this->private;
}
}
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$obj = new MyClass(); echo $obj->public; // Works echo $obj->protected; // Fatal Error echo $obj->private; // Fatal Error $obj->printHello(); // Shows Public, Protected and Private
Visibility (Example 2) Property Visibility
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 $this->private;
}
}
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$obj2 = new MyClass2(); echo $obj2->public; // Works echo $obj2->protected; // Fatal Error echo $obj2->private; // Undefined $obj2->printHello(); // Shows Public2, Protected2, Undefined
Visibility (Example 3) Method Visibility
// Declare a public constructor public function __construct() { }
class MyClass {
// Declare a protected method protected function MyProtected() { }
// Declare a public method public function MyPublic() { }
// This is public function Foo() {
// Declare a private method private function MyPrivate() { }
}
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$myclass = new MyClass; $myclass->MyPublic(); // Works $myclass->MyProtected(); // Fatal Error $myclass->MyPrivate(); // Fatal Error $myclass->Foo(); // Public, Protected and Private work
$this->MyPublic(); $this->MyProtected(); $this->MyPrivate();
}
Visibility (Example 4) Method Visibility
class MyClass2 extends MyClass {
$this->MyPublic(); $this->MyProtected(); $this->MyPrivate(); // Fatal Error
// This is public function Foo2() {
}
}
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$myclass2 = new MyClass2; $myclass2->MyPublic(); // Works $myclass2->Foo2(); // Public and Protected work, not Private
Visibility (Example 5) Method Visibility
class Foo extends Bar {
class Bar {
public function testPublic() { echo "Foo::testPublic\n";
} public function test() { $this->testPrivate(); $this->testPublic();
}
private function testPrivate() { echo "Foo::testPrivate\n";
} public function testPublic() { echo "Bar::testPublic\n";
} }
private function testPrivate() { echo "Bar::testPrivate\n";
$myFoo = new Foo(); $myFoo->test(); // Bar::testPrivate // Foo::testPublic }
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}
Abstract class
− An abstract class is a class that cannot be instantiated on its
own.
abstract class Mathematics{
/*** child class must define these methods ***/ abstract protected function getMessage(); abstract protected function add($num);
/** * method common to both classes **/ public function showMessage() { echo $this->getMessage();
}
22
}
Abstract class
require_once 'Mathematics.php'; class myMath extends Mathematics {
protected function getMessage() { return "The anwser is: ";
}
public function add($num) {
return $num + 2;
}
// A new instance of myMath $myMath = new MyMath (); $myMath->showMessage (); echo $myMath->add (4);
The anwser is: 6
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}
Interfaces
− An interface declares one or more methods. − Must be implemented by any class that implements the
interface.
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)
}
}
24
interface Persistable {
public function save(); public function load(); public function delete();
}
public function save() {
require_once 'Persistable.php'; class Member implements Persistable {
echo "Saving member to
database
";
} public function load() {
private $username; private $location; private $homepage; public function __construct( $username, $location, $homepage ) {
echo "Loading member from
database
";
} public function delete () {
$this->username = $username; $this->location = $location; $this->homepage = $homepage;
echo "Deleting member from
database
";
} public function getUsername() {
}
return $this->username;
}
} public function getLocation() { return $this->location;
} public function getHomepage() {
$m = new Member("Aha", "VN", "No page");
echo $m->getUsername() . "
";
$m->load();
//...
return $this->homepage;
}
Aha Loading member from database
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)
";
} public function save() {
echo "Saving topic to database
";
} public function load() {
echo "Loading topic from database
";
} public function delete () {
echo "Deleting topic from database
";
}
}
Test.php
require_once 'Member.php'; require_once 'Topic.php';
$aMember = new Member ( "TUI", "Viet Nam", "http://example.com" );
echo $aMember->getUsername () . " lives in " . $aMember->getLocation () . "
";
$aMember->save ();
$aTopic = new Topic ( "PHP is Great", $aMember ); $aTopic->showHeader (); $aTopic->save ();
TUI lives in Viet Nam Saving member to database
PHP is Great (created on Saturday 17th Dec 2016 03:00:07 AM by TUI) Saving topic to database
Autoloading classes
− Create a function called __autoload() near the start of
your PHP application.
− PHP automatically calls your __autoload() function.
function __autoload($className) {
require_once ("$className.php"); echo "Loaded $className.php";
}
Loaded Member.php Created object: Member Object ( [username:Member:private] => TUI [location:Member:private] => Viet Nam [homepage:Member:private] => No page )
28
$member = new Member("TUI", "Viet Nam", "No page"); echo "Created object: "; print_r ( $member );
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 $makeGreeting ( 'Jerry', 'afternoon' ) . '';
Good morning, Tom Good afternoon, Jerry
29
Closures
− A closure is an anonymous function that can access variables imported from the outside scope without using any global variables.
function myClosure($num) {
return function ($x) use ($num) {
};
return $num * $x;
}
20 30
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$closure = myClosure ( 10 ); echo $closure ( 2 ); echo $closure ( 3 );
Namespaces
− 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;
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// ... code ...
Cat.php
namespace foo;
Animal.php namespace other\animate;
class Cat {
class Animal {
static function breathes() {
static function says() { echo 'Meoow';
echo 'Air';
}
}
}
}
Dog.php
Test.php
namespace bar;
namespace test;
class Dog {
static function says() { echo 'Ruff';
}
}
