Use PHP arrays like a boss

These are the slides from a talk given at WordCamp Los Angeles 2016.

You’ve heard of the good ol’ school PHP loops. You have your “for” loops, your “foreach” loops, your “while” loops, your “fruit” loops… Well maybe not that last one!

As a WordPress developer, you use arrays and loops all the time. They’re an essential part of your developer toolbox. But do you know everything about them?

PHP has a wealth of array functions. They’re used by PHP experts to make their life easier. They let you reduce the amount of PHP code you need. This helps prevent bugs and makes your code more maintainable.

You’ll learn about functions like array_filter, array_map and array_reduce. All within the context of regular WordPress work. By the end of this talk, loops won’t look at you the same way ever again.

You can read the companion article at: https://carlalexander.ca/php-array-functions-instead-loops/

Transcript

1. Use PHP arrays like a BOSS
2. Carl Alexander
3. @twigpress
4. carlalexander.ca
6. You use arrays a LOT with WordPress
7. You use loops a LOT with these arrays
8. Loops are easy to overuse
9. Makes your code complex
10. Makes your code hard to read
11. Makes your code hard to test
12. PHP has a ton of array functions
13. Relevant concepts
14. Array data type
15. Concept of array in computer science
16. Used to store a collection of values
17. Each value stored at a specific location
18. Retrieved using an index or key
19. Arrays are also used in mathematics
20. with mathematical functions
21. Functional programming
22. Important with PHP array functions
23. Revolves around functions
24. Mathematical ones, not PHP ones
25. What’s special about these functions?
26. They always take an input
27. They always return a value
28. They also come in two categories
29. Higher-order functions
30. Accept functions as arguments
31. Anonymous functions
32. Serve higher-order functions
33. Same as a string or array data type
34. PHP callables
35. Defines a function or method call
36. Also known as a callback
37. They have three different forms
38. Array and string: norm with WordPress
39. Anonymous function: new with PHP 5.3
40. Same type of functions as earlier
41. We can do functional programming!
42. This is what we’ll use to replace loops
43. You can use the other forms in your code
44. Questions?
45. Replacing loops
46. When can you use array functions?
47. Not a definitive list
48. Just a starting point
49. Validating array values
50. Using a loop to remove array values
51. $posts_with_meta_key = get_posts(array( 'meta_key' => ‘post_meta_key') ); $posts_with_valid_meta_key = array(); foreach ($posts_with_meta_key as $post) { if (my_plugin_is_meta_key_valid($post->post_meta_key)) { $posts_with_valid_meta_key[] = $post; } }
52. $posts_with_meta_key = get_posts(array( 'meta_key' => ‘post_meta_key') ); $posts_with_valid_meta_key = array(); foreach ($posts_with_meta_key as $post) { if (my_plugin_is_meta_key_valid($post->post_meta_key)) { $posts_with_valid_meta_key[] = $post; } }
53. $posts_with_meta_key = get_posts(array( 'meta_key' => ‘post_meta_key') ); $posts_with_valid_meta_key = array(); foreach ($posts_with_meta_key as $post) { if (my_plugin_is_meta_key_valid($post->post_meta_key)) { $posts_with_valid_meta_key[] = $post; } }
54. $posts_with_meta_key = get_posts(array( 'meta_key' => ‘post_meta_key') ); $posts_with_valid_meta_key = array(); foreach ($posts_with_meta_key as $post) { if (my_plugin_is_meta_key_valid($post->post_meta_key)) { $posts_with_valid_meta_key[] = $post; } }
55. $posts_with_meta_key = get_posts(array( 'meta_key' => ‘post_meta_key') ); $posts_with_valid_meta_key = array(); foreach ($posts_with_meta_key as $post) { if (my_plugin_is_meta_key_valid($post->post_meta_key)) { $posts_with_valid_meta_key[] = $post; } }
56. $posts_with_meta_key = get_posts(array( 'meta_key' => ‘post_meta_key') ); $posts_with_valid_meta_key = array(); foreach ($posts_with_meta_key as $post) { if (my_plugin_is_meta_key_valid($post->post_meta_key)) { $posts_with_valid_meta_key[] = $post; } }
57. array_filter function
58. Filters the values inside an array
59. You pass it an array and a callable
60. Iterates through each array value
61. Callable decides if value is kept or not
62. Returns filtered array
63. Replacing loop with array_filter
64. $posts_with_meta_key = get_posts(array( 'meta_key' => ‘post_meta_key') ); $posts_with_valid_meta_key = array_filter( $posts_with_meta_key, function(WP_Post $post) { return my_plugin_is_meta_key_valid($post->post_meta_key); } );
65. $posts_with_meta_key = get_posts(array( 'meta_key' => ‘post_meta_key’ )); $posts_with_valid_meta_key = array_filter( $posts_with_meta_key, function(WP_Post $post) { return my_plugin_is_meta_key_valid($post->post_meta_key); } );
66. $posts_with_meta_key = get_posts(array( 'meta_key' => ‘post_meta_key’ )); $posts_with_valid_meta_key = array_filter( $posts_with_meta_key, function(WP_Post $post) { return my_plugin_is_meta_key_valid($post->post_meta_key); } );
67. $posts_with_meta_key = get_posts(array( 'meta_key' => ‘post_meta_key’ )); $posts_with_valid_meta_key = array_filter( $posts_with_meta_key, function(WP_Post $post) { return my_plugin_is_meta_key_valid($post->post_meta_key); } );
68. $posts_with_meta_key = get_posts(array( 'meta_key' => ‘post_meta_key’ )); $posts_with_valid_meta_key = array_filter( $posts_with_meta_key, function(WP_Post $post) { return my_plugin_is_meta_key_valid($post->post_meta_key); } );
69. $posts_with_meta_key = get_posts(array( 'meta_key' => ‘post_meta_key’ )); $posts_with_valid_meta_key = array_filter( $posts_with_meta_key, function(WP_Post $post) { return my_plugin_is_meta_key_valid($post->post_meta_key); } );
70. $posts_with_meta_key = get_posts(array( 'meta_key' => ‘post_meta_key’ )); $posts_with_valid_meta_key = array_filter( $posts_with_meta_key, function(WP_Post $post) { return my_plugin_is_meta_key_valid($post->post_meta_key); } );
71. Questions?
72. Generating new arrays
73. Using a loop to create a new array
74. $recent_posts = get_posts(); $recent_post_permalinks = array(); foreach ($recent_posts as $post) { $recent_post_permalinks[] = get_post_permalink($post->ID); }
75. $recent_posts = get_posts(); $recent_post_permalinks = array(); foreach ($recent_posts as $post) { $recent_post_permalinks[] = get_post_permalink($post->ID); }
76. $recent_posts = get_posts(); $recent_post_permalinks = array(); foreach ($recent_posts as $post) { $recent_post_permalinks[] = get_post_permalink($post->ID); }
77. $recent_posts = get_posts(); $recent_post_permalinks = array(); foreach ($recent_posts as $post) { $recent_post_permalinks[] = get_post_permalink($post->ID); }
78. $recent_posts = get_posts(); $recent_post_permalinks = array(); foreach ($recent_posts as $post) { $recent_post_permalinks[] = get_post_permalink($post->ID); }
79. array_map function
80. Modifies an array using a callable
81. Each array value passed to callable
82. Callable applies changes to it
83. Returns transformed array
84. Replacing loop with array_map
85. $recent_posts = get_posts(); $recent_post_permalinks = array_map( function(WP_Post $post) { return get_post_permalink($post->ID); }, $recent_posts );
86. $recent_posts = get_posts(); $recent_post_permalinks = array_map( function(WP_Post $post) { return get_post_permalink($post->ID); }, $recent_posts );
87. $recent_posts = get_posts(); $recent_post_permalinks = array_map( function(WP_Post $post) { return get_post_permalink($post->ID); }, $recent_posts );
88. $recent_posts = get_posts(); $recent_post_permalinks = array_map( function(WP_Post $post) { return get_post_permalink($post->ID); }, $recent_posts );
89. $recent_posts = get_posts(); $recent_post_permalinks = array_map( function(WP_Post $post) { return get_post_permalink($post->ID); }, $recent_posts );
90. $recent_posts = get_posts(); $recent_post_permalinks = array_map( function(WP_Post $post) { return get_post_permalink($post->ID); }, $recent_posts );
91. $recent_posts = get_posts(); $recent_post_permalinks = array_map( function(WP_Post $post) { return get_post_permalink($post->ID); }, $recent_posts );
92. Transforming array of posts into links
93. Powerful concept
94. Questions?
95. Searching an array
96. Using a loop to get an array value
97. $recent_posts = get_posts(); $longest_recent_post = null; foreach ($recent_posts as $post) { if (!$longest_recent_post instanceof WP_Post || str_word_count($post->post_content) > str_word_count($longest_recent_post->post_content) ) { $longest_recent_post = $post; } }
98. $recent_posts = get_posts(); $longest_recent_post = null; foreach ($recent_posts as $post) { if (!$longest_recent_post instanceof WP_Post || str_word_count($post->post_content) > str_word_count($longest_recent_post->post_content) ) { $longest_recent_post = $post; } }
99. $recent_posts = get_posts(); $longest_recent_post = null; foreach ($recent_posts as $post) { if (!$longest_recent_post instanceof WP_Post || str_word_count($post->post_content) > str_word_count($longest_recent_post->post_content) ) { $longest_recent_post = $post; } }
100. $recent_posts = get_posts(); $longest_recent_post = null; foreach ($recent_posts as $post) { if (!$longest_recent_post instanceof WP_Post || str_word_count($post->post_content) > str_word_count($longest_recent_post->post_content) ) { $longest_recent_post = $post; } }
101. $recent_posts = get_posts(); $longest_recent_post = null; foreach ($recent_posts as $post) { if (!$longest_recent_post instanceof WP_Post || str_word_count($post->post_content) > str_word_count($longest_recent_post->post_content) ) { $longest_recent_post = $post; } }
102. $recent_posts = get_posts(); $longest_recent_post = null; foreach ($recent_posts as $post) { if (!$longest_recent_post instanceof WP_Post || str_word_count($post->post_content) > str_word_count($longest_recent_post->post_content) ) { $longest_recent_post = $post; } }
103. $recent_posts = get_posts(); $longest_recent_post = null; foreach ($recent_posts as $post) { if (!$longest_recent_post instanceof WP_Post || str_word_count($post->post_content) > str_word_count($longest_recent_post->post_content) ) { $longest_recent_post = $post; } }
104. $recent_posts = get_posts(); $longest_recent_post = null; foreach ($recent_posts as $post) { if (!$longest_recent_post instanceof WP_Post || str_word_count($post->post_content) > str_word_count($longest_recent_post->post_content) ) { $longest_recent_post = $post; } }
105. array_reduce function
106. Shrinks an array to a single value
107. Compares array values using callable
108. More complex than earlier callable
109. Callable uses two parameters
110. Current return value
111. Current array value
112. Compare the two and return one of them
113. Replacing loop with array_reduce
114. $recent_posts = get_posts(); $longest_recent_post = array_reduce( $recent_posts, function($longest_post, WP_Post $post) { if (!$longest_post instanceof WP_Post || str_word_count($post->post_content) > str_word_count($longest_post->post_content) ) { return $post; } return $longest_post; } );
115. $recent_posts = get_posts(); $longest_recent_post = array_reduce( $recent_posts, function($longest_post, WP_Post $post) { if (!$longest_post instanceof WP_Post || str_word_count($post->post_content) > str_word_count($longest_post->post_content) ) { return $post; } return $longest_post; } );
116. $recent_posts = get_posts(); $longest_recent_post = array_reduce( $recent_posts, function($longest_post, WP_Post $post) { if (!$longest_post instanceof WP_Post || str_word_count($post->post_content) > str_word_count($longest_post->post_content) ) { return $post; } return $longest_post; } );
117. $recent_posts = get_posts(); $longest_recent_post = array_reduce( $recent_posts, function($longest_post, WP_Post $post) { if (!$longest_post instanceof WP_Post || str_word_count($post->post_content) > str_word_count($longest_post->post_content) ) { return $post; } return $longest_post; } );
118. $recent_posts = get_posts(); $longest_recent_post = array_reduce( $recent_posts, function($longest_post, WP_Post $post) { if (!$longest_post instanceof WP_Post || str_word_count($post->post_content) > str_word_count($longest_post->post_content) ) { return $post; } return $longest_post; } );
119. $recent_posts = get_posts(); $longest_recent_post = array_reduce( $recent_posts, function($longest_post, WP_Post $post) { if (!$longest_post instanceof WP_Post || str_word_count($post->post_content) > str_word_count($longest_post->post_content) ) { return $post; } return $longest_post; } );
120. $recent_posts = get_posts(); $longest_recent_post = array_reduce( $recent_posts, function($longest_post, WP_Post $post) { if (!$longest_post instanceof WP_Post || str_word_count($post->post_content) > str_word_count($longest_post->post_content) ) { return $post; } return $longest_post; } );
121. $recent_posts = get_posts(); $longest_recent_post = array_reduce( $recent_posts, function($longest_post, WP_Post $post) { if (!$longest_post instanceof WP_Post || str_word_count($post->post_content) > str_word_count($longest_post->post_content) ) { return $post; } return $longest_post; } );
122. $recent_posts = get_posts(); $longest_recent_post = array_reduce( $recent_posts, function($longest_post, WP_Post $post) { if (!$longest_post instanceof WP_Post || str_word_count($post->post_content) > str_word_count($longest_post->post_content) ) { return $post; } return $longest_post; } );
123. $recent_posts = get_posts(); $longest_recent_post = array_reduce( $recent_posts, function($longest_post, WP_Post $post) { if (!$longest_post instanceof WP_Post || str_word_count($post->post_content) > str_word_count($longest_post->post_content) ) { return $post; } return $longest_post; } );
124. $recent_posts = get_posts(); $longest_recent_post = array_reduce( $recent_posts, function($longest_post, WP_Post $post) { if (!$longest_post instanceof WP_Post || str_word_count($post->post_content) > str_word_count($longest_post->post_content) ) { return $post; } return $longest_post; } );
125. Questions?
126. Searching for a valid array value
127. Combines two loops from earlier
128. Validates array values
129. But also finds the longest post
130. $posts_with_meta_key = get_posts(array( 'meta_key' => ‘post_meta_key' )); $longest_post_with_valid_meta_key = null; foreach ($posts_with_meta_key as $post) { if (my_plugin_is_meta_key_valid($post->post_meta_key)) { if (!$longest_post_with_valid_meta_key instanceof WP_Post || str_word_count($post->post_content) > str_word_count($longest_post_with_valid_meta_key->post_content) ) { $longest_post_with_valid_meta_key = $post; } } }
131. Please don't do this loop in practice!
132. $posts_with_meta_key = get_posts(array( 'meta_key' => ‘post_meta_key' )); $longest_post_with_valid_meta_key = null; foreach ($posts_with_meta_key as $post) { if (my_plugin_is_meta_key_valid($post->post_meta_key)) { if (!$longest_post_with_valid_meta_key instanceof WP_Post || str_word_count($post->post_content) > str_word_count($longest_post_with_valid_meta_key->post_content) ) { $longest_post_with_valid_meta_key = $post; } } }
133. $posts_with_meta_key = get_posts(array( 'meta_key' => ‘post_meta_key' )); $longest_post_with_valid_meta_key = null; foreach ($posts_with_meta_key as $post) { if (my_plugin_is_meta_key_valid($post->post_meta_key)) { if (!$longest_post_with_valid_meta_key instanceof WP_Post || str_word_count($post->post_content) > str_word_count($longest_post_with_valid_meta_key->post_content) ) { $longest_post_with_valid_meta_key = $post; } } }
134. $posts_with_meta_key = get_posts(array( 'meta_key' => ‘post_meta_key' )); $longest_post_with_valid_meta_key = null; foreach ($posts_with_meta_key as $post) { if (my_plugin_is_meta_key_valid($post->post_meta_key)) { if (!$longest_post_with_valid_meta_key instanceof WP_Post || str_word_count($post->post_content) > str_word_count($longest_post_with_valid_meta_key->post_content) ) { $longest_post_with_valid_meta_key = $post; } } }
135. $posts_with_meta_key = get_posts(array( 'meta_key' => ‘post_meta_key' )); $longest_post_with_valid_meta_key = null; foreach ($posts_with_meta_key as $post) { if (my_plugin_is_meta_key_valid($post->post_meta_key)) { if (!$longest_post_with_valid_meta_key instanceof WP_Post || str_word_count($post->post_content) > str_word_count($longest_post_with_valid_meta_key->post_content) ) { $longest_post_with_valid_meta_key = $post; } } }
136. $posts_with_meta_key = get_posts(array( 'meta_key' => ‘post_meta_key' )); $longest_post_with_valid_meta_key = null; foreach ($posts_with_meta_key as $post) { if (my_plugin_is_meta_key_valid($post->post_meta_key)) { if (!$longest_post_with_valid_meta_key instanceof WP_Post || str_word_count($post->post_content) > str_word_count($longest_post_with_valid_meta_key->post_content) ) { $longest_post_with_valid_meta_key = $post; } } }
137. $posts_with_meta_key = get_posts(array( 'meta_key' => ‘post_meta_key' )); $longest_post_with_valid_meta_key = null; foreach ($posts_with_meta_key as $post) { if (my_plugin_is_meta_key_valid($post->post_meta_key)) { if (!$longest_post_with_valid_meta_key instanceof WP_Post || str_word_count($post->post_content) > str_word_count($longest_post_with_valid_meta_key->post_content) ) { $longest_post_with_valid_meta_key = $post; } } }
138. Combining array functions
139. No new array function!
140. New concept: function composition
141. Used with functional programming
143. No need to create large functions
144. Make functions as small as possible
145. Compose multiple functions together
146. Composing array functions
147. $posts_with_meta_key = get_posts(array( 'meta_key' => ‘post_meta_key' )); $longest_post_with_valid_meta_key = array_reduce( array_filter( $posts_with_meta_key, function(WP_Post $post) { return my_plugin_is_meta_key_valid($post->post_meta_key); } ), function($longest_post, WP_Post $post) { if (!$longest_post instanceof WP_Post || str_word_count($post->post_content) > str_word_count($longest_post->post_content) ) { return $post; } return $longest_post; } );
148. $posts_with_meta_key = get_posts(array( 'meta_key' => ‘post_meta_key' )); $longest_post_with_valid_meta_key = array_reduce( array_filter( $posts_with_meta_key, function(WP_Post $post) { return my_plugin_is_meta_key_valid($post->post_meta_key); } ), function($longest_post, WP_Post $post) { if (!$longest_post instanceof WP_Post || str_word_count($post->post_content) > str_word_count($longest_post->post_content) ) { return $post; } return $longest_post; } );
149. $posts_with_meta_key = get_posts(array( 'meta_key' => ‘post_meta_key' )); $longest_post_with_valid_meta_key = array_reduce( array_filter( $posts_with_meta_key, function(WP_Post $post) { return my_plugin_is_meta_key_valid($post->post_meta_key); } ), function($longest_post, WP_Post $post) { if (!$longest_post instanceof WP_Post || str_word_count($post->post_content) > str_word_count($longest_post->post_content) ) { return $post; } return $longest_post; } );
150. $posts_with_meta_key = get_posts(array( 'meta_key' => ‘post_meta_key' )); $longest_post_with_valid_meta_key = array_reduce( array_filter( $posts_with_meta_key, function(WP_Post $post) { return my_plugin_is_meta_key_valid($post->post_meta_key); } ), function($longest_post, WP_Post $post) { if (!$longest_post instanceof WP_Post || str_word_count($post->post_content) > str_word_count($longest_post->post_content) ) { return $post; } return $longest_post; } );
151. $posts_with_meta_key = get_posts(array( 'meta_key' => ‘post_meta_key' )); $longest_post_with_valid_meta_key = array_reduce( array_filter( $posts_with_meta_key, function(WP_Post $post) { return my_plugin_is_meta_key_valid($post->post_meta_key); } ), function($longest_post, WP_Post $post) { if (!$longest_post instanceof WP_Post || str_word_count($post->post_content) > str_word_count($longest_post->post_content) ) { return $post; } return $longest_post; } );
152. $posts_with_meta_key = get_posts(array( 'meta_key' => ‘post_meta_key' )); $longest_post_with_valid_meta_key = array_reduce( array_filter( $posts_with_meta_key, function(WP_Post $post) { return my_plugin_is_meta_key_valid($post->post_meta_key); } ), function($longest_post, WP_Post $post) { if (!$longest_post instanceof WP_Post || str_word_count($post->post_content) > str_word_count($longest_post->post_content) ) { return $post; } return $longest_post; } );
153. $posts_with_meta_key = get_posts(array( 'meta_key' => ‘post_meta_key' )); $longest_post_with_valid_meta_key = array_reduce( array_filter( $posts_with_meta_key, function(WP_Post $post) { return my_plugin_is_meta_key_valid($post->post_meta_key); } ), function($longest_post, WP_Post $post) { if (!$longest_post instanceof WP_Post || str_word_count($post->post_content) > str_word_count($longest_post->post_content) ) { return $post; } return $longest_post; } );
154. $posts_with_meta_key = get_posts(array( 'meta_key' => ‘post_meta_key' )); $longest_post_with_valid_meta_key = array_reduce( array_filter( $posts_with_meta_key, function(WP_Post $post) { return my_plugin_is_meta_key_valid($post->post_meta_key); } ), function($longest_post, WP_Post $post) { if (!$longest_post instanceof WP_Post || str_word_count($post->post_content) > str_word_count($longest_post->post_content) ) { return $post; } return $longest_post; } );
155. $posts_with_meta_key = get_posts(array( 'meta_key' => ‘post_meta_key' )); $longest_post_with_valid_meta_key = array_reduce( array_filter( $posts_with_meta_key, function(WP_Post $post) { return my_plugin_is_meta_key_valid($post->post_meta_key); } ), function($longest_post, WP_Post $post) { if (!$longest_post instanceof WP_Post || str_word_count($post->post_content) > str_word_count($longest_post->post_content) ) { return $post; } return $longest_post; } );
156. $posts_with_meta_key = get_posts(array( 'meta_key' => ‘post_meta_key' )); $longest_post_with_valid_meta_key = array_reduce( array_filter( $posts_with_meta_key, function(WP_Post $post) { return my_plugin_is_meta_key_valid($post->post_meta_key); } ), function($longest_post, WP_Post $post) { if (!$longest_post instanceof WP_Post || str_word_count($post->post_content) > str_word_count($longest_post->post_content) ) { return $post; } return $longest_post; } );
157. $posts_with_meta_key = get_posts(array( 'meta_key' => ‘post_meta_key' )); $longest_post_with_valid_meta_key = array_reduce( array_filter( $posts_with_meta_key, function(WP_Post $post) { return my_plugin_is_meta_key_valid($post->post_meta_key); } ), function($longest_post, WP_Post $post) { if (!$longest_post instanceof WP_Post || str_word_count($post->post_content) > str_word_count($longest_post->post_content) ) { return $post; } return $longest_post; } );
158. Questions?
159. Why do this?
160. Loops are familiar
161. Using array functions isn’t
162. You won’t always feel that way
163. You’ll get better with time
164. Reduces complexity
165. Improves code quality
166. Prevents technical debt
167. Questions?
168. Thank you!