Object Oriented PHP | OOPs

1. Object Oriented Programming with PHP A Presentation byADMEC Multimedia Institute & Web Development Institute (WDI) Delhi Twitter: @admecinstitute www.admecindia.co.in www.web-development-institute.com

2. PHP Presentation’s Purpose • The purpose of this PHP presentation is to explain Object Oriented PHP in brief. • This PHP presentation can help a PHP programmer in understanding the terms and terminologies used in practical object oriented PHP. • Frameworks of PHP like CodeIgniter, CakePHP, Symphony, Zend etc are MVC based and knowledge of Object Oriented PHP will help in understanding all them. www.admecindia.co.in www.web-development-institute.com

3. Topics to be Covered • Basics of OOP in PHP • Object & Classes in OOP • Magic Function in PHP OOP • Inheritance (Extending a class) • Visibility (public, private, protected) • Abstract Classes in PHP • Static Methods and properties in PHP • Interfaces in PHP • Explaining PHP Class Functions • Describing Autoload in PHP www.admecindia.co.in www.web-development-institute.com

4. Concept and Basics of PHP • PHP is a scripting language • Specially a Procedural Programming • Not a true OO Programming • It supports few OO features • Full OOP Support added as of PHP5

5. What is OOP • It is Object Oriented Programming method of coding. • Allow developer to group multiple similar tasks into classes. • The main aim of OOP is to not repeat the similar code again and again. • With OOP, it is easy to maintain the structure of application and organizing the data • OOP provide simplicity to the complex applications code. www.admecindia.co.in www.web-development-institute.com

6. Why is OOP Useful in PHP? • Code organization and maintainability • Add clarity • Reduce complexity • Simple rules allow complex interactions • Emphasizes data over procedure • Code modularity or refactoring • Code reusability • Well-suited for databases

7. Do You Need OOP? • It depends • My PHP OOP rule of thumb • For a simple site, OOP adds unnecessary complexity • For a complex site, OOP adds necessary simplicity

8. Classes & Objects in PHP Concept of classes & objects can be explained with these two images: • A class, for example, is like a blueprint for a house. It defines the shape of the house on paper, with relationships between the different parts of the house clearly defined and planned out, even though the house doesn't exist. • An object, then, is like the actual house built according to that blueprint. The data stored in the object is like the wood, wires, and concrete that compose the house: without being assembled according to the blueprint, it's just a pile of stuff. However, when it all comes together, it becomes an organized, useful house. www.admecindia.co.in www.web-development-institute.com

9. Classes & Objects in PHP In PHP class is created using class keyword as shown in the following example classmyOwnClass{ //variables of the classvar $variable1;var $variable2; //Function of class function mergeVariable() { return $this->variable1 . $this->variable2; }} www.admecindia.co.in www.web-development-institute.com

10. Classes & Objects in PHP There is no use of classes without objects. Object is representative of your class. If created a class then you must need to create object of the class to solve your problem using class. You can create object of your class by using new keyword. $objClass = new myClass(); Now in above code you are creating object of class myClass in variable $objClass. You can create multiple object of your same class. Every object is different from other. $objClass1 = new myClass();$objClass2 = new myClass(); www.admecindia.co.in www.web-development-institute.com

11. Magic Functions in PHP OOP Magic methods in php are some predefined function by php compiler which executes on some event. Magic methods starts with prefix __, for example __call, __get, __set. List of Magic Functions in PHP www.admecindia.co.in www.web-development-institute.com

12. Magic Functions in PHP OOP www.admecindia.co.in www.web-development-institute.com

13. Magic Functions in PHP OOP www.admecindia.co.in www.web-development-institute.com

14. Visibility in PHP There are 3 type of visibility available in PHP for controlling your property or method. • Public: Public method or variable can be accessible from anywhere. I mean from inside the class, out side the class and in child(will discuss in next chapter) class also. • Private: Method or property with private visibility can only be accessible inside the class. You can not access private method or variable from outside of your class. • Protected: Method or variable with protected visibility can only be access in the derived class. Or in other word in child class. Protected will be used in the process of inheritance. www.admecindia.co.in www.web-development-institute.com

15. Abstract Classes in PHP • The abstract classes and methods are used to create a model of minimum required methods which must be defined in normal sub-classes derived from an abstract class (with extends). • An abstract class is created with the abstract keyword. • An abstract class cannot be instantiated, can only be inherited by other sub-classes extended from it. • The abstract methods are declared with the abstract keyword, and cannot have an implementation, they simply declare the method's signature. abstract public function method Name($arguments); www.admecindia.co.in www.web-development-institute.com

16. Abstract Classes in PHP In this example is created an abstract class with a property ($name), an abstract method ( greetName() ) and a normal method ( setName() ). <?php // AbstractClass class abstract class AbstractClass { protected $name; // declare an abstract method abstract public function greetName($greet); // define a normal method public function setName($name) { $this->name = $name; // sets the value of $name property } } ?> www.admecindia.co.in www.web-development-institute.com

17. Static Methods & Properties in PHP • Static methods and properties in php is very useful feature. • Static methods and properties in php can directly accessible without creating object of class. • Your php class will be static class if your all methods and properties of the class is static.  • Static Methods and Properties in PHP will be treated as public if no visibility is defined. • Static properties of class is a property which is directly accessible from class with the help of ::(scope resolution operator). You can declare static  property using static keyword. www.admecindia.co.in www.web-development-institute.com

18. Interfaces in PHP • You can define a common structure for your classes using interfaces. • An Interface is like a template similar to abstract classwith a difference where it uses only abstract methods. • In simple words, an interface is like a class usinginterface keyword and contains only functiondeclarations(function with no body). • An Interface should be implemented in the class and all themethods or functions should be overridden in this class. • It is the place where we can define the function.When a class use that interface in that class the total function body part will describe.after that we can call that function in other class and we are get result. www.admecindia.co.in www.web-development-institute.com

19. Interfaces in PHP Example of interface: • interface InterfaceName{ function fun1(); function fun2(a,b); }class ClassName implements InterfaceName{fuction fun1(){ function implementation....... }fuction fun2(a,b){ function implementation....... }}  www.admecindia.co.in www.web-development-institute.com

20. Differences between an Abstract Class and an Interface in PHP • For abstract class a method must be declared as abstract. Abstract methods doesn’t have any implementation. • The Abstract methods can declare with Access modifiers like public, internal, protected. When implementing in subclass these methods must be defined with the same (or a less restricted) visibility. • Abstract class can contain variables and concrete methods. • A class can Inherit only one Abstract class and Multiple inheritance is not possible for Abstract class. For interface all the methods by default are abstract methods only. So one cannot declare variables or concrete methods in interfaces. All methods declared in an interface must be public. Interfaces cannot contain variables and concrete methods except constants. A class can implement many interfaces and Multiple interface inheritance is possible. www.admecindia.co.in www.web-development-institute.com

21. PHP Class Functions in PHP PHP has available several class functions to help you through the OOP mine field. • get_declared_interfaces() • class_exists() • get_class() • get_declared_classes() • Each of these is shown here beginning with the get_declared_interfaces(). www.admecindia.co.in www.web-development-institute.com

22. PHP Class Functions in PHP get_declared_interfaces() following function provides an array of all the available declared interfaces. <?phpinterface fax{  public function dial();  public function send();  public function recieve();}interface printer{  public function printBlack();  public function printColor();  public function printDraft();  public function kick();}/*** our interface implementation ***/class printerFax implements fax, printer{  public function dial(){ }  public function send(){ }  public function recieve(){ } www.admecindia.co.in www.web-development-institute.com

23. PHP Class Functions in PHP   public function printBlack(){ }  public function printColor(){ }  public function printDraft(){ }  public function kick(){ } }  /*** create and printerfax object ***/  $object = new printerFax;  /*** get the declared interfaces ***/foreach(get_declared_interfaces() as $key=>$interface)        {        echo $key.' =&gt; '.$interface.'<br />';        }?> www.admecindia.co.in www.web-development-institute.com

24. Other Functions in PHP • get_class() • class_exists() • get_declared_classes • <?php/*** a pretend class ***/class fax{  public function dial(){ }  public function send(){ }  public function recieve(){ }}/*** another pretend class ***/class printer{  public function printBlack(){ }  public function printColor(){ }  public function printDraft(){ }  public function kick(){ }} www.admecindia.co.in www.web-development-institute.com

25. Other Functions in PHP /*** create an instance of the fax class ***/$foo = new fax;/*** create an instance of the printer class ***/$bar = new printer;echo '$foo is from the ' get_class($foo).' class<br />';echo class_exists("printer").'<br />';echo 'Declared classes are:<br /> ';foreach(get_declared_classes() as $key=>$classname)    {    echo $key.' -&gt; '.$classname.'<br />';    }?> www.admecindia.co.in www.web-development-institute.com

26. Autoload in PHP • Many developers writing object-oriented applications create one PHP source file per class definition. One of the biggest annoyances is having to write a long list of needed includes at the beginning of each script (one for each class). • In PHP 5, this is no longer necessary. You may define an __autoload() function which is automatically called in case you are trying to use a class/interface which hasn't been defined yet. By calling this function the scripting engine is given a last chance to load the class before PHP fails with an error. www.admecindia.co.in www.web-development-institute.com

27. Autoload in PHP <?php/*** include our class definitions ***/include('classes/vehicle.class.php');include('classes/motorcycle.class.php');include('classes/printer.class.php');include('classes/printer.class.php');/*** instantiate a new vehicle class object ***/$vehicle = new vehicle;*** instantiate a new motorcycle class object ***/$bike = new motorcycle;*** instantiate a new printer class object ***/$printer = new printer;*** instantiate a new fax class object ***/$fax = new fax;?> www.admecindia.co.in www.web-development-institute.com

28. Autoload in PHP With __autoload() the above code can be reduce to following <?php/*** Autoload class files ***/function __autoload($class){  require('classes/' . strtolower($class) . '.class.php');}/*** instantiate a new vehicle class object ***/$vehicle = new vehicle;/*** instantiate a new motorcycle class object ***/$bike = new motorcycle;/*** instantiate a new printer class object ***/$printer = new printer;/*** instantiate a new fax class object ***/$fax = new fax;?> www.admecindia.co.in www.web-development-institute.com

29. ADMEC Multimedia Institute • For more info you can visit • www.admecindia.co.inand www.web-development-institute.com • For course related enquiry, ring us at: • 9811-81-81-22, 011-3203-5055 Created by: Parul Sabal Guided by: Ravi Bhadauria www.admecindia.co.in www.web-development-institute.com