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- PHÁT TRIỂN PHẦN MỀM NGUỒN MỞ
OBJECT ORIENTED PROGRAMMING
Nguyễn Hữu Thể
- Content
1. Class
2. Visibility
3. Properties & Methods
4. Getter & Setter
5. Create objects
6. Constructor
7. Destructor
8. Inheritance
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
PHP JAVA
class Person class Person
{ {
private $name; private String name;
private $age; private int age;
public function getName(){ public String getName(){
return $this->name; return name;
} }
public function setName($name){ public void setName(String name){
$this->name = $name; this.name = name;
} }
public function getAge(){ public int getAge(){
return $this->age; return age;
} }
public function setAge($age){ public void setAge(int 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!";
}
$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.";
$p->show(); 8
- __set() method
class SetName {
public function __set($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
9
- __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];
}
}
$candy = new GetName ();
// set a non existant property
echo 'Value of property is: ' . $candy->milk; $choctype property with index of: milk
10
Value of property is: 0
- Constructor
public function __construct() {
//...
}
public function __construct($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 $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();
Nguyễn Lê is 20 years old! Salary: 200 16
- 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
echo $obj->private; // Fatal Error
$obj->printHello(); // Shows Public, Protected and Private
17
- 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;
}
}
$obj2 = new MyClass2();
echo $obj2->public; // Works
echo $obj2->protected; // Fatal Error
echo $obj2->private; // Undefined
$obj2->printHello(); // Shows Public2, Protected2, Undefined
18
- 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() { }
// This is public
function Foo() {
$this->MyPublic(); $myclass = new MyClass;
$this->MyProtected(); $myclass->MyPublic(); // Works
$this->MyPrivate(); $myclass->MyProtected(); // Fatal Error
} $myclass->MyPrivate(); // Fatal Error
} $myclass->Foo(); // Public, Protected and Private work 19
- Visibility (Example 4)
Method Visibility
class MyClass2 extends MyClass
{
// This is public
function Foo2()
{
$this->MyPublic();
$this->MyProtected();
$this->MyPrivate(); // Fatal Error
}
}
$myclass2 = new MyClass2;
$myclass2->MyPublic(); // Works
$myclass2->Foo2(); // Public and Protected work, not Private
20
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