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
2. Carl Alexander
3. @twigpress
4. carlalexander.ca
6. Heard of object-oriented programming
7. Tried to use it with WordPress
8. Didn’t feel useful
9. Common problem
10. Hard to design classes that work well with WordPress
11. Why?
12. Going back to the beginning
13. WordPress didn't start off using object-oriented programming
14. PHP didn’t even support it well
15. All procedural programming
16. What is procedural programming?
17. Programming using steps
18. Each line of code is a step towards the outcome that you're looking for
19. It’s how you break down problems
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 $results; }
21. function get_authors_registered_after($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 $results; }
22. function get_authors_registered_after($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 $results; }
23. function get_authors_registered_after($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 $results; }
24. function get_authors_registered_after($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 $results; }
25. function get_authors_registered_after($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 $results; }
26. How do you convert this?
27. Move everything in a class
28. class Authors { public function get_registered_after($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 $results; } }
29. class Authors { public function get_registered_after($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 $results; } }
30. class Authors { public function get_registered_after($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; } }
31. This isn't object-oriented programming
32. You put your procedural code inside a class method
33. That's why using object-oriented programming with WordPress feels bad
34. Everyone tells you to structure code that way
35. Perpetuates this cycle of misunderstanding
36. Questions?
37. Understanding object-oriented programming
38. Use classes working together to solve problems
39. No steps like procedural programming
40. Programming using Legos (!!!)
41. Classes: Templates used to create objects
42. Lego brick types
43. Objects: Individual instances of a class
44. Lego bricks
45. Why isn't using object-oriented programming as easy as using Legos?
46. Already have way of doing things
47. Also not the complete picture
48. Object-oriented programming with WordPress
49. Not just using Legos to build things
50. Designing whole Lego sets
51. You have to visualize the Lego set
52. You have to design the Lego brick types
53. You have to assemble the Lego set
54. A lot more than just building something with Legos
55. Most developers don't have to do this
56. Object-oriented frameworks do most of the heavy lifting for you
57. They're the Lego Group
58. They give you the Lego brick types
59. They give you the instructions
60. Original analogy works with frameworks
61. Has important implications
62. Similar footing with developers using a framework
63. Neither of you knows how to think like the Lego Group
64. You don't have a choice to learn how to think that way
65. Will make you a much better developer
66. Questions?
67. Thinking like the Lego Group
68. Hard thing to do
69. Strategy to start designing classes better
70. Break the problem down into smaller parts
71. Think about all the Lego brick types you might need
72. What does a WordPress plugin need?
73. class AdminPage
74. class Options
75. class Plugin
76. class Metabox
77. Classes representing common WordPress elements
78. Also have to think about what’s specific to your plugin
79. E-commerce plugin?
80. class Product
81. class Sale
82. Learning management system plugin?
83. class Course
84. class Students
85. Break your plugin or theme into classes
86. Some will be specific to WordPress
87. Others to what you're building
88. Add code to them next
89. Properties to store data
90. Methods to define behaviour
91. Where things get complicated
92. No right or wrong way to do it
93. Don’t expect to get this all right on the first try
94. Might need to break things down into more classes
95. Might not know how to solve a specific problem
96. Might have made some wrong assumptions
97. All part of the process
98. Different for everyone
99. Identical outcome at the end
100. Classes are no longer empty
101. Start piecing these different classes together into a Lego set
102. Review Break things down Add code
103. Repeating this cycle is the key
104. Only difference is how fast you do it
105. Questions?
106. Thank you!