WordPress: To OOP or not to OOP

Thoughts on incremental structure in larger software projects, the WordPress community, and few OOP examples

Transcript

1. To OOP or not to OOP Nikolay Bachiyski, WordCamp Europe 2013
2. Nikolay
3. Automattic
4. http://extrapolate.me/ @nikolayb github://nb
5. Next 25 minutes:
6. 0.Why should we care?
7. 1. How WordPress developers see OOP
8. 2. Better OOP
9. 0. Why should we care?
10. WordPress is BIG
12. 120K Lines of PHP
13. Needs some structure Lines of PHP
14. Structure
15. No Structure
16. Not many rules
17. Each small piece is easy to understand
18. Hard to change & improve
19. Impossible to understand deeply
22. Structure = Modules + Communication
28. Structure → Code
29. Choices in PHP: Procedural and OOP
30. Procedural
31. ↑ Perceived simplicity
32. ↓ Hard to hide implementation
33. ↓ Prefix all the things (<5.3)
34. ↓ Data sharing using globals only
35. ↓ Hard to test
36. OOP
37. ↓ Perceived complicatedness
38. 1. How WordPress developers see OOP
39. A big reason WP is so popular is because it is not infatuated with the latest, greatest developer lust objects… “
40. One of the biggest problems I've found with OOP is that it forces the developer to bake in structure long before the developer actually understands what that structure should be… “
41. Classes==Good
42. OOP == Bad
43. ?
44. One of the biggest problems I've found with OOP is that it forces the developer to bake in structure long before the developer actually understands what that structure should be… “
45. One of the biggest problems I've found with OOP is that it forces the developer to bake in structure long before the developer actually understands what that structure should be… “
46. Forces = always happens?
47. Building Useful Abstractions is HARD
48. Very Hard
49. Either refuse responsibility
50. Or try
51. Fail
52. Learn
54. Try again
55. Fail better
57. Succeed
59. OOP can be good
60. Do one thing, do it well
63. class WP_Screen { function get( $hook_name = '' ); function set_current_screen(); function in_admin( $admin = null ); function add_old_compat_help( $screen, $help ); function set_parentage( $parent_file ); function add_option( $option, $args = array() ); function get_option( $option, $key = false ); function get_help_tabs(); function get_help_tab( $id ); function add_help_tab( $args ); function remove_help_tab( $id ); function remove_help_tabs(); function get_help_sidebar(); function set_help_sidebar( $content ); function get_columns(); function render_screen_meta(); function show_screen_options(); function render_screen_options(); function render_screen_layout(); function render_per_page_options(); }
64. class WP_Screen { function get( $hook_name = '' ); function set_current_screen(); function in_admin( $admin = null ); function add_old_compat_help( $screen, $help ); function set_parentage( $parent_file ); function add_option( $option, $args = array() ); function get_option( $option, $key = false ); function get_help_tabs(); function get_help_tab( $id ); function add_help_tab( $args ); function remove_help_tab( $id ); function remove_help_tabs(); function get_help_sidebar(); function set_help_sidebar( $content ); function get_columns(); function render_screen_meta(); function show_screen_options(); function render_screen_options(); function render_screen_layout(); function render_per_page_options(); }
65. Responsible for <action> or Represents a <thing>
66. No And’s, Or’s, or But’s
67. Short!
68. The big idea is “messaging” [...] The key in making great and growable systems is much more to design how its modules communicate rather than what their internal properties and behaviors should be. “
69. Innocuous inheritance
70. WP_Image_Editor
71. WP_Image_Editor_Imagick extends WP_Image_Editor
72. WP_Image_Editor_GD extends WP_Image_Editor
73. Common logic in all subclasses
74. if ( ! $this->make_image( $filename, 'imagejpeg', array( $image, $filename, apply_filters( 'jpeg_quality', $this- >quality, 'image_resize' ) ) ) ) $this->image->setImageCompressionQuality ( apply_filters( 'jpeg_quality', $quality, 'image_resize' ) ); GD: ImageMagick:
75. GD: ImageMagick: protected function update_size( $width = null, $height = null ) { … return parent::update_size( $width, $height ); } protected function update_size( $width = null, $height = null ) { … return parent::update_size( $width, $height ); }
76. Change in interface = change in every subclass
77. How to spot?
78. IS-A vs. HAS-A/USES
79. Inheritance for reuse
80. Gravatar widget is a WP Widget ✅✓
81. ImagickMagick is an Image Editor
82. WP Image Editor uses ImagickMagick
83. WP Image Editor uses GD
84. WP Image Editor has an image
85. Composition
86. $this->engine = new WP_Image_Engine_GD(); $this->engine = new WP_Image_Engine_ImageMagick(); $this->image = $this->engine->load( $filename ); $new_size = $this->image->update_size();
87. function save( $filename = null, $mime_type = null ) { … $jpeg_quality = apply_filters( 'jpeg_quality', … ); $this->image->save( $filename, $mime_type, array( 'jpeg_quality' => $jpeg_quality ) ); … }
88. What to remember?
89. Communication between modules is everything
90. Structure is hard
91. We can’t get better without trying and failing first
93. Growing Object-Oriented Software, Guided by Tests http://www.growing-object-oriented-software.com/
94. ?