Bài giảng Phát triển phần mềm nguồn mở: Bài 4 - Nguyễn Hữu Thể

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Bài 4 trình bày về lập trình hướng đối tượng "object oriented programming". Nội dung chính trong chương này gồm có: Class, visibility, properties & methods, Getter & getter, create objects, constructor, destructor, inheritance, abstract class, interfaces, autoloading classes, anonymous functions, closures, namespace. Mời các bạn cùng tham khảo.

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Nội dung Text: Bài giảng Phát triển phần mềm nguồn mở: Bài 4 - Nguyễn Hữu Thể

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