PHP. Main object oriented features (from php5 power programming)

Transcription

1 PHP Main object oriented features (from php5 power programming)

2 OO Model A OOP is a collection of objects An object has properties State (private data) An object has methods Every object is an instance of a class

3 Main characteristic public/private/protected access modifiers for methods and properties. Allows the use of common OO access modifiers to control access to methods and properties class MyClass private $id = 18; public function getid() return $this->id;

4 Constructor Unified constructor name construct()..or define a function with the same name of the class Like in PHP4 class MyClass function construct() print "Inside constructor";

5 Example (1/2) class Person private $name; function setname($name) $this->name = $name; function getname() return $this->name; ; $judy = new Person(); $judy->setname("judy"); $joe = new Person(); $joe->setname("joe"); print $judy->getname(). "\n"; //print Judy print $joe->getname(). "\n"; //print Joe

6 Example (2/2) class Person function construct($name) $this->name = $name; function getname() return $this->name; private $name; ; Same as before _construct is called by new It may have parameters It cannot return a value $judy = new Person("Judy"); $joe = new Person("Joe"); print $judy->getname(); print $joe->getname();

7 Destructor destruct() Called when an object is destroyed (no more reference) class MyClass function destruct() print "An object of type MyClass is being destroyed\n"; $obj = new MyClass(); $obj = NULL; An object of type MyClass is being destroyed

8 Access protection of member variables class MyDbConnectionClass public $queryresult; protected $dbhostname = "localhost"; private $connectionhandle; //... class MyFooDotComDbConnectionClass extends MyDbConnectionClass protected $dbhostname = "foo.com";

9 Static properties class MyUniqueIdClass self: refer to the current class static $idcounter = 0; public $uniqueid; function construct() self::$idcounter++; $this->uniqueid = self::$idcounter; $obj1 = new MyUniqueIdClass(); print $obj1->uniqueid. "\n"; //print 1 $obj2 = new MyUniqueIdClass(); print $obj2->uniqueid. "\n"; //print 2

10 Cloning objects class MyClass public $var = 1; obj1 obj2 object $obj1 = new MyClass(); $obj2 = $obj1; $obj2->var = 2; print $obj1->var; //print 2 obj1 obj2 object object $obj1 = new MyClass(); $obj2 = clone $obj1; $obj2->var = 2; print $obj1->var; //print 1

11 POLYMORPHISM Single class inheritance like Java Multiple interface implementations Final keyword class Child extends Parent... class A implements B, C, interface I1 extends I2, I3,......

12 Autoload When writing object-oriented code, it is often customary to put each class in its own source file. Using the _autoload() function (one per application) a class can be included at runtime

13 general.inc <?php function autoload($class_name) require_once($_server["document_root"]. "/classes/$class_name.php");?> file has same name of the class Myclass.php <?php class MyClass function printhelloworld() print "Hello, World\n";?> must be placed in /classes directory main.php autoload called if MyClass is not defined <?php require_once "general.inc"; $obj = new MyClass(); // calls autoload $obj->printhelloworld();?>

14 Reflection Allows to have class information at runtime Just an example <?php class C function F() print "Hello, World\n"; ReflectionClass::export("C");?> - Constants [0] - Static properties [0] - Static methods [0] - Properties [0] - Methods [1] Method [ public method F ]

15 Example Managing password in a database Design a class for adding user and checking user identity

16 Example: create a table CREATE TABLE users ( VARCHAR(128) NOT NULL PRIMARY KEY, passwd CHAR(40) NOT NULL );

17 <?php class Auth function Auth() mysql_connect('localhost', 'user', 'password'); mysql_select_db('my_own_bookshop'); public function adduser($ , $password) $q = ' INSERT INTO users( , passwd) VALUES ( '. $ . ", '. sha1($password). ") '; mysql_query($q);

18 public function authuser($ , $password) $q = ' SELECT * FROM users WHERE = '. $ . ' " AND passwd = '. sha1($password). ' " '; $r = mysql_query($q); if (mysql_num_rows($r) == 1) return TRUE; else return FALSE;?>

19 LAB Write a class for Complex numbers

20 Using PEAR Just Run the gopear.bat file Use the pear commands to update package Pear upgrade XML_RPC

21 LAB: Use GeoName from Google <?php $new_include_path = "C:/PHP/PEAR/"; set_include_path($new_include_path); require_once 'Services/GeoNames.php'; $geo = new Services_GeoNames(); $cities = $geo->search(array('name_equals' => 'Roma')); echo "List of cities named Roma:\n"; foreach($cities as $city) printf(" - %s (%s)<br>", $city->name, $city->countryname); echo "\n";?>