1. Beginners Guide to Object Orientation In PHP by Rick Ogden for PHPNW09

2. What is Object Orientation?

Object-Oriented Programming is a programming methodology that consists of multiple interacting objects, each completely self-sufficient.

This allows for flexible, expandable programming 3. Encapsulated code 4. Protection of data 5. Many more things beyond the scope of this tutorial

6. Class

A class is a blueprint of an object, and is the basis of what the object will consist of. It contains two major entities:

Properties 7. Methods 8. A class is self sufficient by nature, and therefore can be implemented into multiple applications without modification.

9. Example of a Class

Here we're going to create a new class for containing someone's profile information on a social networking website.

10. Object

An object is created by creating a new instance of a class. Objects of the same class have exactly the same functionality, but the properties within the object are what makes them different. Eg. A news article on a website may be an object from a NewsArticle class, but the contents of the article will differ from another news article

11. Referencing

In order for an object to be useful, you need to be able to call its contents. For this, PHP uses the arrow operator ( -> ).

$object->property; 12. $object->method();

13. Self Referencing

Throughout the instance of an object, chances are it will need to reference itself (to get its properties, or call its own methods). In order for an object to reference itself, the variable $this is used in the class.

$this->property; 14. $this->method();

15. Properties

Properties are class-wide variables. 16. They are often initialised when an object of the class is created (although they do not have to be) 17. They are defined at the top of the class 18. Methods can alter and interact with these properties throughout the existence of the object

19. Adding Properties

We will add some properties to our Profile class. Of course the properties are not limited to the ones here:

20. Methods

A method is a piece of code within a class which performs a task or calculation. These are similar to functions. It can:

Interact and modify properties of the object 21. Take arguments on execution 22. Return a value after execution 23. None of these are compulsory (although if it doesn't do any of these, it's a bit useless!)

24. Method Uses

Methods are used for a number of different things. These include:

Retrieve data from a property in a read only fashion 25. Format data 26. Alter properties in a controlled way

27. Method: Parameters

A method can include parameters (exactly like functions) 28. Parameters can either be required, or have a default value

29. Constructor

The constructor is called when the object is initialised.

A constructor often takes parameters to initialise some (if not all) of the properties of that object 30. It is identified in a class as it has the method name __construct (for backwards-compatibility, a method with the same name as the class also works)

31. Our class so far

I've added a constructor to initialise the properties 32. Added a method to return the full name of the person whose profile it is.

33. 34. Instantiate an Object

To create an object from a class you use the new keyword.

• $object = new MyClass();

This creates a new object and calls the constructor 35. Any arguments that need to be given to the instructor are given on creation. 36. We will store our class in Profile.php

37. Why Use Encapsulation

Encapsulation gives the ability to hide data from outside of the object.

Gives the programmer control over what is inputted into properties (validation etc..) 38. What form data is when it is returned from the class 39. Ability to alter code within the class, without having to worry about needing to change code in other parts of the application

40. Public/Private/Protected

Properties and methods can take one of 3 forms to encapsulate

Public: Property/method can be accessed from anywhere, inside or outside the object 41. Protected: Can only be accessed from within the class, or inherited class 42. Private: Can only be accessed from directly within the class (and not subclasses)

43. 44. Inheritance

Inheritance allows a programmer to reuse a class and expand it for a different purpose. Reasons:

Add code to a class to make it more specialised 45. Override existing code 46. Why reinvent the wheel?

47. Cons of Object Orientation

Object Orientation does not come without its drawbacks 48. Main reason is it is less efficient than procedural code

49. Thank You Any Questions? For these slides and other things please visit my brand new website: http://www.rickogden.com/