Object Oriented PHP Overview
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Object-oriented PHP provides several advantages over functional programming including easier maintenance and reuse of code through inheritance, polymorphism, and design patterns. Key concepts in OO PHP include classes, objects, inheritance, access modifiers, static methods/attributes, and cloning vs object references. An example photo gallery application is described that utilizes objects like User, Photograph, and Comment along with design patterns like strategy, iterator, and singleton.
Object Oriented PHP Overview
- 1. OO PHP Object Oriented PHP
- 2. OO PHP Object Oriented PHP Advantages over functional programming • Systematic procedure for designing application by extracting nouns and verbs from specifications and using CRC (Classes, Responsibilities, Collaborators) Cards, then formation of a UML diagram. • Much, much easier to maintain and add or change functionality • Elimination of repetitious code - DRY (Don’t repeat yourself) • Enables use of design patterns – super efficient algorithms that have evolved for accomplishing common OOP application functionality
- 3. Universal Modeling Language (Horstmann, 2010) Inheritance – “is a” Aggregation – “has a” Dependency – collaborating classes Interface – contract for concrete implementation
- 4. Fundamental Concepts • Inheritance - extends override methods Object Oriented PHP for Beginners http://www.killerphp.com/tutorials/object-oriented-php/ • Setting Access Modifiers • public, private, protected Use getter/setter methods and private instance variables (attributes) • Static Method or Attribute – belongs to the class, not the object instance (e.g., counters) • Scope resolution operator - error if cannot resolve Paamayim Nekudotayim* Referencing Parent Class – self:: parent:: works with parent static or instance methods but not parent attributes, as well as $this-> refers to instance Constructors/Destructors – give a default value __construct($var=0){} Cloning Objects clone keyword and __clone() * Error Message in Hebrew method paam = One • Comparing Objects == vs. === ayim = Doubled nekudot = Dot ayim = Doubled
- 6. Cloning vs. Object references
- 7. Design Patterns • The Strategy Pattern defines a family of algorithms, encapsulates each • The Iterator Pattern provides a way to one, and makes them access the elements of an aggregate interchangeable (polymorphism). object sequentially without exposing its Strategy lets the algorithm vary underlying representation. independently from the clients that • The Adaptor Pattern changes the use it. interface of one or more classes • The Template Method pattern allows • The Decorator Pattern attaches a programmer to define the skeleton additional responsibilities to an object of an algorithm in a superclass and dynamically. Decorators provide a delegate specific steps to a subclass. flexible alternative to subclassing. Subclasses can redefine certain steps • The Singleton Pattern ensures a class of an algorithm without changing the only has one instance and provides a algorithm's structure. global point of access to it.
- 8. Project Overview • Photo gallery Thumbnail view • Full image view • Comments • Pagination
- 9. Project Overview • Administration Back End Login • Create Admin users • Upload images Delete Images • Review/Delete Comments
- 10. Objects User Photograph Comment These will also serve as database tables. Usually when you have a database table you have an object for that table. • Database • singleton pattern and allows for adaptor pattern use if database format changes, e.g., from MySQL to Oracle Session Additional Requirements • Pagination • Thumbnail generation
- 11. UML Diagram
- 12. Helpful Links Object Oriented PHP for Beginners http://www.killerphp.com/tutorials/object-oriented-php/
- 13. References Freeman, Eric., Freeman, Elisabeth, Sierra, K., Bates, B. (2004). Head first design patterns. Sebastpol, CA: O’Reilly Media, Inc. Horstmann, C. (2010). Big Java 4th edition. (pp. 512-513). United States of America: John Wiley & Sons, Inc. Koffman, E. (2010). Data structures: abstraction and design using Java. (pp. 685-694). United States of America: John Wiley & Sons, Inc. Lynda.com. (2009, March 25). PHP with MySQL beyond the basics. Retrieved from http://www.lynda.com/tutorial/653