Embracing change

PHP Sount West, 17th June 2015

Transcript

1. EMBRACING CHANGE JAKUB ZALAS 17th June 2015 @jakub_zalas @jakzal
5. DEFER COMMITMENT Decisions are hard to change if software components are tightly coupled.
6. DEFER COMMITMENT We need loosely coupled and highly cohesive components to introduce changes easily.
7. COUPLING & COHESION
8. COHESION Cohesion describes how closely are elements in a module related
9. c l a s s P a c k a g e C r a w l e r { p u b l i c f u n c t i o n c r a w l ( ) { $ c h = c u r l _ i n i t ( ) ; c u r l _ s e t o p t ( $ c h , C U R L O P T _ U R L , ' h t t p : / / a c m e . c o m / ' ) ; c u r l _ s e t o p t ( $ c h , C U R L O P T _ R E T U R N T R A N S F E R , 1 ) ; $ r e s p o n s e = c u r l _ e x e c ( $ c h ) ; c u r l _ c l o s e ( $ c h ) ; / / @ t o d o e x t r a c t d e t a i l s f r o m t h e r e s p o n s e . . . } }
10. SINGLE RESPONSIBILITY PRINCIPLE A module should have one reason to change.
11. SINGLE RESPONSIBILITY PRINCIPLE Gather together the things that change for the same reasons. Separate those things that change for different reasons. http://blog.8thlight.com/uncle-bob/2014/05/08/SingleReponsibilityPrinciple.html
13. COUPLING Modules are coupled if changing one of them requires changing another one. Martin Fowler http://martinfowler.com/ieeeSoftware/coupling.pdf
14. COUPLING
15. COUPLING THROUGH A PROPERTY u s e B u z z \ B r o w s e r ; c l a s s C r a w l e r { / * * * @ v a r B r o w s e r * / p r i v a t e $ b r o w s e r ; }
16. COUPLING THROUGH A METHOD CALL c l a s s C r a w l e r { p r i v a t e $ c ; p u b l i c f u n c t i o n c r a w l ( $ u r l ) { $ t h i s - > c - > g e t B r o w s e r ( ) - > g e t ( $ u r l ) ; } }
17. COUPLING THROUGH A REFERENCE u s e B u z z \ B r o w s e r ; c l a s s C r a w l e r { p u b l i c f u n c t i o n c r a w l ( $ u r l , B r o w s e r $ b ) { $ r e s p o n s e = $ b - > g e t ( $ u r l ) ; } }
18. COUPLING THROUGH A REFERENCE u s e B u z z \ B r o w s e r ; c l a s s C r a w l e r { / * * * @ r e t u r n B r o w s e r * / p u b l i c f u n c t i o n c r a w l ( $ u r l ) { / / . . . r e t u r n $ b r o w s e r ; } }
19. COUPLING THROUGH AN IMPLEMENTATION / EXTENSION u s e B u z z \ B r o w s e r ; c l a s s C r a w l e r e x t e n d s B r o w s e r { p u b l i c f u n c t i o n c r a w l ( $ u r l ) { $ t h i s - > g e t ( $ u r l ) ; } }
20. INCREASING COHESION u s e B u z z \ B r o w s e r ; c l a s s P a c k a g e C r a w l e r { p r i v a t e $ b r o w s e r ; p u b l i c f u n c t i o n _ _ c o n s t r u c t ( B r o w s e r $ b r o w s e r ) { $ t h i s - > b r o w s e r = $ b r o w s e r ; } p u b l i c f u n c t i o n c r a w l ( ) { $ r e s p o n s e = $ t h i s - > b r o w s e r - > g e t ( ' / ' ) ; / / . . . } }
24. Count dependencies c l a s s P r o d u c t C o n t r o l l e r e x t e n d s C o n t r o l l e r { p u b l i c f u n c t i o n s e a r c h A c t i o n ( $ k e y w o r d s ) { $ p r o d u c t s = $ t h i s - > g e t ( ' d o c t r i n e ' ) - > g e t R e p o s i t o r y ( ' A c m e : P r o d u c t ' ) ; - > s e a r c h ( $ k e y w o r d s ) ; r e t u r n $ t h i s - > r e n d e r ( ' p r o d u c t / s e a r c h . h t m l . t w i g ' , [ ' p r o d u c t s ' = > $ p r o d u c t s ] ) ; } }
26. THE DEPENDENCY INVERSION PRINCIPLE
27. HIGH-LEVEL MODULES SHOULD NOT DEPEND ON LOW-LEVEL MODULES. u s e B u z z \ B r o w s e r ; c l a s s P a c k a g e C r a w l e r { p r i v a t e $ b r o w s e r ; p u b l i c f u n c t i o n _ _ c o n s t r u c t ( B r o w s e r $ b r o w s e r ) { $ t h i s - > b r o w s e r = $ b r o w s e r ; } p u b l i c f u n c t i o n c r a w l ( $ r e s o u r c e ) { $ r e s p o n s e = $ t h i s - > b r o w s e r - > g e t ( $ r e s o u r c e ) ; / / . . . } }
28. HIGH-LEVEL MODULES SHOULD NOT DEPEND ON LOW-LEVEL MODULES.
29. BOTH SHOULD DEPEND ON ABSTRACTIONS.
30. BOTH SHOULD DEPEND ON ABSTRACTIONS. i n t e r f a c e H t t p C l i e n t { p u b l i c f u n c t i o n g e t ( $ r e s o u r c e ) ; }
31. BOTH SHOULD DEPEND ON ABSTRACTIONS. c l a s s P a c k a g e C r a w l e r { p r i v a t e $ h t t p C l i e n t ; p u b l i c f u n c t i o n _ _ c o n s t r u c t ( H t t p C l i e n t $ h t t p C l i e n t ) { $ t h i s - > h t t p C l i e n t = $ h t t p C l i e n t ; } p u b l i c f u n c t i o n c r a w l ( ) { $ r e s p o n s e = $ t h i s - > h t t p C l i e n t - > g e t ( ' / ' ) ; / / @ t o d o p a r s e } }
32. BOTH SHOULD DEPEND ON ABSTRACTIONS.
33. BOTH SHOULD DEPEND ON ABSTRACTIONS. u s e B u z z \ B r o w s e r ; c l a s s B u z z H t t p C l i e n t i m p l e m e n t s H t t p C l i e n t { p r i v a t e $ b r o w s e r ; p u b l i c f u n c t i o n _ _ c o n s t r u c t ( B r o w s e r $ b r o w s e r ) { $ t h i s - > b r o w s e r = $ b r o w s e r ; } p u b l i c f u n c t i o n g e t ( $ r e s o u r c e ) { r e t u r n ( s t r i n g ) $ t h i s - > b r o w s e r - > g e t ( $ r e s o u r c e ) ; } }
34. ABSTRACTIONS SHOULD NOT DEPEND UPON DETAILS.
35. DETAILS SHOULD DEPEND UPON ABSTRACTIONS.
36. i n t e r f a c e C o n t e n t P r o v i d e r { p u b l i c f u n c t i o n f e t c h ( $ r e s o u r c e ) ; }
37. c l a s s P a c k a g e C r a w l e r { p r i v a t e $ c o n t e n t P r o v i d e r ; p u b l i c f u n c t i o n _ _ c o n s t r u c t ( C o n t e n t P r o v i d e r $ p r o v i d e r ) { $ t h i s - > c o n t e n t P r o v i d e r = $ p r o v i d e r ; } p u b l i c f u n c t i o n c r a w l ( ) { $ c o n t e n t = $ t h i s - > c o n t e n t P r o v i d e r - > f e t c h ( ' / ' ) ; / / @ t o d o p a r s e } }
38. u s e B u z z \ B r o w s e r ; c l a s s B u z z C o n t e n t P r o v i d e r i m p l e m e n t s C o n t e n t P r o v i d e r { p r i v a t e $ b r o w s e r ; p u b l i c f u n c t i o n _ _ c o n s t r u c t ( B r o w s e r $ b r o w s e r ) { $ t h i s - > b r o w s e r = $ b r o w s e r ; } p u b l i c f u n c t i o n f e t c h ( ) { r e t u r n ( s t r i n g ) $ t h i s - > b r o w s e r - > g e t ( ' / ' ) ; } }
41. u s e G u z z l e \ C l i e n t ; c l a s s G u z z l e C o n t e n t P r o v i d e r i m p l e m e n t s C o n t e n t P r o v i d e r { p r i v a t e $ g u z z l e ; p u b l i c f u n c t i o n _ _ c o n s t r u c t ( C l i e n t $ g u z z l e ) { $ t h i s - > g u z z l e = $ g u z z l e ; } p u b l i c f u n c t i o n f e t c h ( $ r e s o u r c e ) { $ r e q u e s t = $ t h i s - > g u z z l e - > c r e a t e R e q u e s t ( ' G E T ' , $ r e s o u r c e ) ; $ r e s p o n s e = $ r e q u e s t - > s e n d ( ) ; r e t u r n $ r e s p o n s e - > g e t B o d y ( ) ; } }
43. What about the framework? c l a s s P r o d u c t C o n t r o l l e r e x t e n d s C o n t r o l l e r { p u b l i c f u n c t i o n s e a r c h A c t i o n ( $ k e y w o r d s ) { $ p r o d u c t s = $ t h i s - > g e t ( ' d o c t r i n e ' ) - > g e t R e p o s i t o r y ( ' A c m e : P r o d u c t ' ) ; - > s e a r c h ( $ k e y w o r d s ) ; r e t u r n $ t h i s - > r e n d e r ( ' p r o d u c t / s e a r c h . h t m l . t w i g ' , [ ' p r o d u c t s ' = > $ p r o d u c t s ] ) ; } }
45. i n t e r f a c e P r o d u c t R e p o s i t o r y { / * * * @ r e t u r n P r o d u c t [ ] * / p u b l i c f u n c t i o n s e a r c h ( $ k e y w o r d s ) ; }
46. c l a s s D o c t r i n e P r o d u c t R e p o s i t o r y i m p l e m e n t s P r o d u c t R e p o s i t o r y { p r i v a t e $ e m ; p u b l i c f u n c t i o n _ _ c o n s t r u c t ( E n t i t y M a n a g e r $ e m ) { $ t h i s - > e m = $ e m ; } / * * * @ r e t u r n P r o d u c t [ ] * / p u b l i c f u n c t i o n s e a r c h ( $ k e y w o r d s ) { r e t u r n $ t h i s - > e m - > c r e a t e Q u e r y B u i l d e r ( ) - > s e l e c t ( ' p ' ) - > f r o m ( P r o d u c t : : c l a s s , ' p ' ) - > w h e r e ( ' p . t i t l e L I K E : k e y w o r d s ' ) - > s e t P a r a m e t e r ( ' k e y w o r d s ' , ' % ' . $ k e y w o r d s . ' % ' ) - > g e t Q u e r y ( ) - > g e t R e s u l t ( ) ; } }
47. c l a s s P r o d u c t C o n t r o l l e r { p r i v a t e $ p r o d u c t R e p o s i t o r y ; p r i v a t e $ t e m p l a t i n g ; p u b l i c f u n c t i o n _ _ c o n s t r u c t ( P r o d u c t R e p o s i t o r y $ p r o d u c t R e p o s i t o r y , E n g i n e I n t e r f a c e $ t e m p l a t i n g ) { $ t h i s - > p r o d u c t R e p o s i t o r y = $ p r o d u c t R e p o s i t o r y ; $ t h i s - > t e m p l a t i n g = $ t e m p l a t i n g ; } / / . . . }
48. c l a s s P r o d u c t C o n t r o l l e r { / / . . . p u b l i c f u n c t i o n s e a r c h A c t i o n ( $ k e y w o r d s ) { $ p r o d u c t s = $ t h i s - > p r o d u c t R e p o s i t o r y - > s e a r c h ( $ k e y w o r d s ) ; r e t u r n $ t h i s - > t e m p l a t i n g - > r e n d e r R e s p o n s e ( ' p r o d u c t / s e a r c h . h t m l . t w i g ' , [ ' p r o d u c t s ' = > $ p r o d u c t s ] ) ; } }
53. Good code doesn't take more time to write. What takes a lot of time is the learning how to write good code.
54. THANK YOU! @jakub_zalas @jakzal