An Introduction to Object-Oriented Programming, Design Patterns, and Test-Driven Development

A talk given at WordCamp Singapore 2016. Notes and resources available on GitHub here: https://github.com/jacklenox/introduction-to-oop

Transcript

1. An Introduction... ...to Object­Oriented Programming, Design Patterns, and Test­Driven Development By Jack Lenox ( WordPress.com VIP )
2. Slides are available at: github.com/jacklenox/introduction­to­oop
3. Introducing the introduction What is Object­Oriented Programming?
4. "Object­oriented programming (OOP) is a programming paradigm based on the concept of "objects", which may contain data, in the form of fields, often known as attributes; and code, in the form of procedures, often known as methods." Wikipedia
7. C++ Delphi Objective­C Java C# .NET Ruby
8. PHP 5 (July 2006)
9. WordPress Est. 2003
10. So, what is not OOP?
11. "Normal" PHP tends to come under the banner of Procedural Programming
12. Procedural Programming Linear Written in the order it's executed Not necessarily modular
13. Procedural Form Submission < ? p h p i f ( i s s e t ( $ _ P O S T [ ' n a m e ' ] ) ) { $ n a m e = s a n i t i z e _ t e x t _ f i e l d ( $ _ P O S T [ ' n a m e ' ] ) ; i f ( s t r l e n ( $ n a m e ) < 6 ) { e c h o ' N a m e n o t l o n g e n o u g h ' ; e x i t ; } } ? > / / F o r m i n p u t e t c .
14. Object­Oriented Programming Non­linear Series of self­contained objects that can work together Modular by design
15. Benefits Reduced possibility of naming clashes Modularity Reusability
16. Why and when to OOP?
18. Car Attributes: Colour: Yellow Doors: 2 Luggage rack: true Methods: Accelerate Brake Steer
19. Blog post Attributes: Title: My awesome blog post! Date: 2016­09­06 Sticky: false Methods: Update Publish Delete
20. How to OOP?
21. Language Classes Attributes Methods p r i v a t e , p r o t e c t e d , p u b l i c
22. Class c l a s s C a r { / / C l a s s b o d y }
23. A class is a blueprint for the objects that we want to produce
24. Attributes c l a s s C a r { p u b l i c $ c o l o r ; p u b l i c $ d o o r s ; p u b l i c $ l u g g a g e _ r a c k ; }
25. Methods c l a s s C a r { f u n c t i o n a c c e l e r a t e ( ) { e c h o ' T y r e s q u e a l ! ' ; } f u n c t i o n b r a k e ( ) { e c h o ' S c r e e c h ' ; } f u n c t i o n s t e e r ( $ d e g r e e ) { e c h o " S t e e r b y $ d e g r e e d e g r e e s " ; } }
26. Car Factory c l a s s C a r { p u b l i c $ c o l o r = ' w h i t e ' ; p u b l i c $ d o o r s = 2 ; p u b l i c $ l u g g a g e _ r a c k = f a l s e ; f u n c t i o n a c c e l e r a t e ( ) { e c h o ' T y r e s q u e a l ! ' ; } f u n c t i o n b r a k e ( ) { e c h o ' S c r e e c h ' ; } f u n c t i o n s t e e r ( $ d e g r e e ) { e c h o " S t e e r b y $ d e g r e e d e g r e e s " ; } }
27. Build a Car $ n e w _ c a r = n e w C a r ( ) ;
28. Build a Yellow Car with Two Doors $ y e l l o w _ c a r = n e w C a r ( ) ; $ y e l l o w _ c a r ­ > c o l o r = " y e l l o w " ; $ y e l l o w _ c a r ­ > d o o r s = 4 ;
29. Could Do Better?
30. Introducing _ _ c o n s t r u c t c l a s s C a r { p u b l i c $ c o l o r ; p u b l i c $ d o o r s ; p u b l i c $ l u g g a g e _ r a c k ; f u n c t i o n _ _ c o n s t r u c t ( $ c o l o r , $ d o o r s , $ l u g g a g e _ r a c k ) { $ t h i s ­ > c o l o r = $ c o l o r ; $ t h i s ­ > d o o r s = $ d o o r s ; $ t h i s ­ > l u g g a g e _ r a c k = $ l u g g a g e _ r a c k ; } / / M e t h o d s g o h e r e }
31. Build a Purple Car with Four Doors and a Luggage Rack $ p u r p l e _ c a r = n e w C a r ( ' p u r p l e ' , 4 , t r u e ) ;
32. Documentation Say hello to phpDocumentor
33. Documenting Classes / * * * D e f i n e s c a r f a c t o r y . * T h e c a r c l a s s p r o d u c e s c a r s * * @ p a c k a g e c a r * @ a u t h o r J a c k L e n o x * @ c o p y r i g h t 2 0 1 6 A u t o m a t t i c I n c . * / c l a s s C a r { / / C l a s s b o d y }
34. Documenting Properties c l a s s C a r { / * * * T h e c a r c o l o r . * U s e d b y t h e m a n u f a c t u r i n g p r o c e s s * @ v a r s t r i n g * / p u b l i c $ c o l o r ; / * * * T h e n u m b e r o f d o o r s . * A l s o u s e d b y t h e m a n u f a c t u r i n g p r o c e s s * @ v a r i n t e g e r * / p u b l i c $ d o o r s ; / * * * W h e t h e r o r n o t t h e c a r h a s a l u g g a g e r u c k . * Y o u ' v e g u e s s e d i t , a l s o f o r m a n u f a c t u r i n g * @ v a r b o o l * / p u b l i c $ l u g g a g e _ r a c k ; / / . . .
35. Documenting Methods / / . . . / * * * A c c e l e r a t e t o m o v e t h e c a r f o r w a r d s . * A c c e l e r a t i o n i s c u r r e n t l y n o t v a r i a b l e s o t h i s * m e t h o d w i l l r e t u r n a s q u e a l f r o m t h e t y r e s a s * t h e w h e e l s s p i n . * @ r e t u r n s t r i n g * / f u n c t i o n a c c e l e r a t e ( ) { r e t u r n ' T y r e s q u e a l ! ' ; } / / . . .
36. Unit Testing and Test­Driven Development Say hello to PHPUnit
37. A Basic Test u s e P H P U n i t \ F r a m e w o r k \ T e s t C a s e ; r e q u i r e _ o n c e ( ' c l a s s ­ c a r . p h p ' ) ; c l a s s C a r T e s t e x t e n d s T e s t C a s e { p r i v a t e $ c a r ; p u b l i c f u n c t i o n s e t U p ( ) { $ t h i s ­ > c a r = n e w C a r ( ' y e l l o w ' , 4 , t r u e ) ; } p u b l i c f u n c t i o n t e a r D o w n ( ) { } p u b l i c f u n c t i o n t e s t G e t C a r ( ) { $ t h i s ­ > a s s e r t E q u a l s ( $ t h i s ­ > c a r ­ > c o l o r , ' y e l l o w ' ) ; $ t h i s ­ > a s s e r t E q u a l s ( $ t h i s ­ > c a r ­ > d o o r s , 4 ) ; $ t h i s ­ > a s s e r t T r u e ( $ t h i s ­ > c a r ­ > l u g g a g e _ r a c k ) ; } }
38. Run the Test $ p h p u n i t ­ ­ v e r b o s e t e s t s P H P U n i t 5 . 5 . 4 b y S e b a s t i a n B e r g m a n n a n d c o n t r i b u t o r s . R u n t i m e : P H P 7 . 0 . 8 ­ 0 u b u n t u 0 . 1 6 . 0 4 . 2 . 1 / 1 ( 1 0 0 % ) T i m e : 1 0 5 m s , M e m o r y : 8 . 0 0 M B O K ( 1 t e s t , 3 a s s e r t i o n s )
39. Design Patterns
40. Singletons and Inheritance
41. OOP and WP in Practice Widgets API The Walker Class WP_Rewrite
42. Widgets API c l a s s M y _ W i d g e t e x t e n d s W P _ W i d g e t { / * * * S e t s u p t h e w i d g e t s n a m e e t c * / p u b l i c f u n c t i o n _ _ c o n s t r u c t ( ) { $ w i d g e t _ o p s = a r r a y ( ' c l a s s n a m e ' = > ' m y _ w i d g e t ' , ' d e s c r i p t i o n ' = > ' M y W i d g e t i s a w e s o m e ' , ) ; p a r e n t : : _ _ c o n s t r u c t ( ' m y _ w i d g e t ' , ' M y W i d g e t ' , $ w i d g e t _ o p s ) ; } / / / C o n t i n u e s . . .
43. / * * * O u t p u t s t h e c o n t e n t o f t h e w i d g e t * * @ p a r a m a r r a y $ a r g s * @ p a r a m a r r a y $ i n s t a n c e * / p u b l i c f u n c t i o n w i d g e t ( $ a r g s , $ i n s t a n c e ) { / / o u t p u t s t h e c o n t e n t o f t h e w i d g e t } / * * * O u t p u t s t h e o p t i o n s f o r m o n a d m i n * * @ p a r a m a r r a y $ i n s t a n c e T h e w i d g e t o p t i o n s * / p u b l i c f u n c t i o n f o r m ( $ i n s t a n c e ) { / / o u t p u t s t h e o p t i o n s f o r m o n a d m i n }
44. / * * * P r o c e s s i n g w i d g e t o p t i o n s o n s a v e * * @ p a r a m a r r a y $ n e w _ i n s t a n c e T h e n e w * o p t i o n s * @ p a r a m a r r a y $ o l d _ i n s t a n c e T h e p r e v i o u s * o p t i o n s * / p u b l i c f u n c t i o n u p d a t e ( $ n e w _ i n s t a n c e , $ o l d _ i n s t a n c e ) { / / p r o c e s s e s w i d g e t o p t i o n s t o b e s a v e d } }
45. The Walker Class ( code.tutsplus.com/tutorials/understanding­ the­walker­class­­wp­25401 )
46. Conclusion
47. WPPB ( wppb.me ) Tom McFarlin's Tuts+ Series ( tommcfarlin.com/object­oriented­ programming­in­wordpress/ )
48. When not to OOP?
49. Trouser­Oriented Clothing, Noun­ Oriented Language etc.
50. Functional Programming? Execution in the Kingdom of Nouns ( steve­yegge.blogspot.sg/2006/03/execution­in­ kingdom­of­nouns.html )
51. OOP is not necessarily the "right way"
52. But it's much better than this!
53. Thank you github.com/jacklenox/introduction­to­oop automattic.com/work­with­us/