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
   

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2. Nikolay
   

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3. Automattic
   

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4. http://extrapolate.me/
   @nikolayb
   github://nb
   

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5. Next 25 minutes:
   

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6. 0.Why should we care?
   

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7. 1. How WordPress
   developers see OOP
   

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8. 2. Better OOP
   

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9. 0. Why should we care?
   

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10. WordPress is BIG
    

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12. 120K Lines of PHP
    

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13. Needs some structure
    Lines of PHP
    

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14. Structure
    

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15. No Structure
    

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16. Not many rules
    

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17. Each small piece is
    easy to understand
    

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18. Hard to change &
    improve
    

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19. Impossible to
    understand deeply
    

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22. Structure
    =
    Modules + Communication
    

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28. Structure → Code
    

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29. Choices in PHP:
    Procedural and OOP
    

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30. Procedural
    

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31. ↑ Perceived simplicity
    

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32. ↓ Hard to hide
    implementation
    

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33. ↓ Prefix all the things
    (<5.3)
    

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34. ↓ Data sharing using
    globals only
    

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35. ↓ Hard to test
    

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36. OOP
    

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37. ↓ Perceived
    complicatedness
    

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38. 1. How WordPress
    developers see OOP
    

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39. A big reason WP is so popular is
    because it is not infatuated with
    the latest, greatest developer
    lust objects…
    “
    

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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…
    “
    

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41. Classes==Good
    

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42. OOP == Bad
    

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43. ?
    

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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…
    “
    

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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…
    “
    

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46. Forces = always
    happens?
    

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47. Building Useful
    Abstractions is HARD
    

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48. Very Hard
    

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49. Either refuse
    responsibility
    

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50. Or try
    

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51. Fail
    

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52. Learn
    

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54. Try again
    

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55. Fail better
    

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57. Succeed
    

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59. OOP can be good
    

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60. Do one thing, do it well
    

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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();
    }
    

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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();
    }
    

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65. Responsible for
    or
    Represents a
    

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66. No And’s, Or’s,
    or But’s
    

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67. Short!
    

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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.
    “
    

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69. Innocuous inheritance
    

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70. WP_Image_Editor
    

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71. WP_Image_Editor_Imagick
    extends
    WP_Image_Editor
    

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72. WP_Image_Editor_GD
    extends
    WP_Image_Editor
    

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73. Common logic in all
    subclasses
    

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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:
    

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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 );
    }
    

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76. Change in interface =
    change in every
    subclass
    

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77. How to spot?
    

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78. IS-A vs. HAS-A/USES
    

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79. Inheritance for reuse
    

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80. Gravatar widget is a
    WP Widget
    ✅✓
    

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81. ImagickMagick is an
    Image Editor
    

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82. WP Image Editor uses
    ImagickMagick
    

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83. WP Image Editor uses
    GD
    

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84. WP Image Editor has
    an image
    

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85. Composition
    

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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();
    

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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 ) );
    …
    }
    

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88. What to remember?
    

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89. Communication
    between modules is
    everything
    

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90. Structure is hard
    

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91. We can’t get better
    without trying and
    failing first
    

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93. Growing Object-Oriented Software,
    Guided by Tests
    http://www.growing-object-oriented-software.com/
    

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94. ?
    

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