GeekAustin PHP Class - Session 6
- 1. Beginning PHP Session #6 January 5, 2011 Josh Butts
- 2. Agenda • Freebies from Zend • OOP
- 3. What are Objects • Programming constructs • Represent a real-life entity • Store data (state) • Implement behaviors
- 4. Object Oriented Programming • ...programming with objects • Use objects to model real world concepts in your code • Objects encapsulate pieces of logic or data • Objects are easy to re-use
- 5. Terms • Class - the definition of an object; what does it represent, what can it do • Instance - an actual object variable in memory
- 6. Classes & Instances • A class is defined in code as you write your program • An instance happens when you program actually runs
- 7. Example User Class Instance of User $username $password jimbojsb $email password $firstname josh@joshbutts.com $lastname Josh Butts authenticate() createPassword() getPosts()
- 8. Classes & Instances • A class is defined in code as you write your program • An instance happens when you program actually runs
- 9. “Static” • Static describes a class or part of a class that can be used without actually creating an instance and filling it with data • Pieces of data that are the same for every instance of a class • Logic that operates on generic data rather than modifying a specific instance’s state
- 10. Building Objects • Properties (variables) • Methods (functions) • Methods & Properties can both be static or not
- 11. Constructors • A special method (1 per object) that gets called when you get a new instance • Does any utility or setup work needed before the instance is ready to be used • Optional • Usually take one or more parameters
- 12. PHP Objects • Preferably you define one class per file • Objects are always passed by reference instead of by value • :: operator is used for static properties and methods • -> operator is used for instance properties and methods
- 13. PHP Objects • self - refers to the current object in a static manner • $this - refers to the current instance
- 14. Special Methods • __construct() • __destruct() • __toString() • many others, for a later discussion