How to approach object-oriented programming with WordPress

These are the slides from a talk given at WordCamp Miami 2019.

You're a WordPress developer who wants to use object-oriented programming in their next project. You're already familiar with concepts like inheritance. The issue is that you're not sure how to apply those concepts to design classes that feel useful.

This isn't something to feel ashamed about! In fact, it's a common problem when trying to use object-oriented programming with WordPress. It's hard to know how to design classes that work well with WordPress.

Well, you're in luck! This is what we'll go over during this talk.

We'll start by going over the prevalent class design in the WordPress ecosystem. We'll analyze what it's doing and why it leaves you feeling unsatisfied.

Then we'll look at how object-oriented programming expects you to design classes. We'll finish by looking at strategies that you can use to design classes. This should let you finally design classes that feel meaningful to use!

You can read the companion article at: https://carlalexander.ca/approaching-object-oriented-programming-wordpress

Transcript

1. object-oriented programming
   with WordPress
   How to approach
   

   View Slide

2. Carl Alexander
   

   View Slide

3. @twigpress
   

   View Slide

4. carlalexander.ca
   

   View Slide

5. View Slide

6. Heard of object-oriented programming
   

   View Slide

7. Tried to use it with WordPress
   

   View Slide

8. Didn’t feel useful
   

   View Slide

9. Common problem
   

   View Slide

10. Hard to design classes that
    work well with WordPress
    

    View Slide

11. Why?
    

    View Slide

12. Going back to the beginning
    

    View Slide

13. WordPress didn't start off using
    object-oriented programming
    

    View Slide

14. PHP didn’t even support it well
    

    View Slide

15. All procedural programming
    

    View Slide

16. What is procedural programming?
    

    View Slide

17. Programming using steps
    

    View Slide

18. Each line of code is a step towards the
    outcome that you're looking for
    

    View Slide

19. It’s how you break down problems
    

    View Slide

20. function get_authors_registered_after($date, $number = 5)
    {
    $results = array();
    $authors = get_users('who=authors');
    foreach ($authors as $author) {
    if ($author->user_registered > $date) {
    $results[] = $author;
    }
    if (count($results) >= $number) {
    break;
    }
    }
    return $results;
    }
    

    View Slide

21. function get_authors_registered_after($date, $number = 5)
    {
    $results = array();
    $authors = get_users('who=authors');
    foreach ($authors as $author) {
    if ($author->user_registered > $date) {
    $results[] = $author;
    }
    if (count($results) >= $number) {
    break;
    }
    }
    return $results;
    }
    

    View Slide

22. function get_authors_registered_after($date, $number = 5)
    {
    $results = array();
    $authors = get_users('who=authors');
    foreach ($authors as $author) {
    if ($author->user_registered > $date) {
    $results[] = $author;
    }
    if (count($results) >= $number) {
    break;
    }
    }
    return $results;
    }
    

    View Slide

23. function get_authors_registered_after($date, $number = 5)
    {
    $results = array();
    $authors = get_users('who=authors');
    foreach ($authors as $author) {
    if ($author->user_registered > $date) {
    $results[] = $author;
    }
    if (count($results) >= $number) {
    break;
    }
    }
    return $results;
    }
    

    View Slide

24. function get_authors_registered_after($date, $number = 5)
    {
    $results = array();
    $authors = get_users('who=authors');
    foreach ($authors as $author) {
    if ($author->user_registered > $date) {
    $results[] = $author;
    }
    if (count($results) >= $number) {
    break;
    }
    }
    return $results;
    }
    

    View Slide

25. function get_authors_registered_after($date, $number = 5)
    {
    $results = array();
    $authors = get_users('who=authors');
    foreach ($authors as $author) {
    if ($author->user_registered > $date) {
    $results[] = $author;
    }
    if (count($results) >= $number) {
    break;
    }
    }
    return $results;
    }
    

    View Slide

26. How do you convert this?
    

    View Slide

27. Move everything in a class
    

    View Slide

28. class Authors
    {
    public function get_registered_after($date, $number = 5)
    {
    $results = array();
    $authors = get_users('who=authors');
    foreach ($authors->results as $author) {
    if ($author->user_registered > $date) {
    $results[] = $author;
    }
    if (count($results) >= $number) {
    break;
    }
    }
    return $results;
    }
    }
    

    View Slide

29. class Authors
    {
    public function get_registered_after($date, $number = 5)
    {
    $results = array();
    $authors = get_users('who=authors');
    foreach ($authors->results as $author) {
    if ($author->user_registered > $date) {
    $results[] = $author;
    }
    if (count($results) >= $number) {
    break;
    }
    }
    return $results;
    }
    }
    

    View Slide

30. class Authors
    {
    public function get_registered_after($date, $number = 5)
    {
    $results = array();
    $authors = get_users('who=authors');
    foreach ($authors->results as $author) {
    if ($author->user_registered > $date) {
    $results[] = $author;
    }
    if (count($results) >= $number) {
    break;
    }
    }
    return $results;
    }
    }
    

    View Slide

31. This isn't object-oriented programming
    

    View Slide

32. You put your procedural code
    inside a class method
    

    View Slide

33. That's why using object-oriented
    programming with WordPress feels bad
    

    View Slide

34. Everyone tells you to
    structure code that way
    

    View Slide

35. Perpetuates this cycle of
    misunderstanding
    

    View Slide

36. Questions?
    

    View Slide

37. Understanding
    object-oriented programming
    

    View Slide

38. Use classes working together
    to solve problems
    

    View Slide

39. No steps like procedural programming
    

    View Slide

40. Programming using Legos (!!!)
    

    View Slide

41. Classes:
    Templates used to create objects
    

    View Slide

42. Lego brick types
    

    View Slide

43. Objects:
    Individual instances of a class
    

    View Slide

44. Lego bricks
    

    View Slide

45. Why isn't using object-oriented
    programming as easy as using Legos?
    

    View Slide

46. Already have way of doing things
    

    View Slide

47. Also not the complete picture
    

    View Slide

48. Object-oriented programming
    with WordPress
    

    View Slide

49. Not just using Legos to build things
    

    View Slide

50. Designing whole Lego sets
    

    View Slide

51. You have to
    visualize the Lego set
    

    View Slide

52. You have to
    design the Lego brick types
    

    View Slide

53. You have to
    assemble the Lego set
    

    View Slide

54. A lot more than just
    building something with Legos
    

    View Slide

55. Most developers don't have to do this
    

    View Slide

56. Object-oriented frameworks
    do most of the heavy lifting for you
    

    View Slide

57. They're the Lego Group
    

    View Slide

58. They give you the Lego brick types
    

    View Slide

59. They give you the instructions
    

    View Slide

60. Original analogy works with frameworks
    

    View Slide

61. Has important implications
    

    View Slide

62. Similar footing with
    developers using a framework
    

    View Slide

63. Neither of you knows
    how to think like the Lego Group
    

    View Slide

64. You don't have a choice
    to learn how to think that way
    

    View Slide

65. Will make you a much better developer
    

    View Slide

66. Questions?
    

    View Slide

67. Thinking like the Lego Group
    

    View Slide

68. Hard thing to do
    

    View Slide

69. Strategy to start designing classes better
    

    View Slide

70. Break the problem down
    into smaller parts
    

    View Slide

71. Think about all the Lego brick types
    you might need
    

    View Slide

72. What does a WordPress plugin need?
    

    View Slide

73. class AdminPage
    

    View Slide

74. class Options
    

    View Slide

75. class Plugin
    

    View Slide

76. class Metabox
    

    View Slide

77. Classes representing
    common WordPress elements
    

    View Slide

78. Also have to think about
    what’s specific to your plugin
    

    View Slide

79. E-commerce plugin?
    

    View Slide

80. class Product
    

    View Slide

81. class Sale
    

    View Slide

82. Learning management system plugin?
    

    View Slide

83. class Course
    

    View Slide

84. class Students
    

    View Slide

85. Break your plugin or theme
    into classes
    

    View Slide

86. Some will be specific to WordPress
    

    View Slide

87. Others to what you're building
    

    View Slide

88. Add code to them next
    

    View Slide

89. Properties to store data
    

    View Slide

90. Methods to define behaviour
    

    View Slide

91. Where things get complicated
    

    View Slide

92. No right or wrong way to do it
    

    View Slide

93. Don’t expect to get this all right
    on the first try
    

    View Slide

94. Might need to break things down
    into more classes
    

    View Slide

95. Might not know how to solve
    a specific problem
    

    View Slide

96. Might have made some
    wrong assumptions
    

    View Slide

97. All part of the process
    

    View Slide

98. Different for everyone
    

    View Slide

99. Identical outcome at the end
    

    View Slide

100. Classes are no longer empty
     

     View Slide

101. Start piecing these different classes
     together into a Lego set
     

     View Slide

102. Review
     Break things down
     Add code
     

     View Slide

103. Repeating this cycle is the key
     

     View Slide

104. Only difference is how fast you do it
     

     View Slide

105. Questions?
     

     View Slide

106. Thank you!
     

     View Slide