Introduction to building WordPress plugins and things to consider when building plugins for public distribution.

1. SO YOU WANT TO
BUILD AND RELEASE
A PLUGIN…
Ryan Duff
WordCamp Raleigh 2015

2. ABOUT ME
• Started using and
developing for WordPress
in 2004
• Plugin Developer
• Meetup Organizer

3. A BIT OF PLUGIN
HISTORY

4. my-hacks.php
https://wordpress.org/news/2003/12/new-feature-my-hacksphp/

5. VERSION 1.2
(May 22, 2004)

6. Plugin API

7. THINGS TO
CONSIDER

8. YOUR CODE

9. FILTERS

10. apply_filters( $tag, $value, $var ... )
http://codex.wordpress.org/Function_Reference/apply_filters

11. EXAMPLE
$query_args = array(
'post_type' => 'books',
‘posts_per_page' => 5,
'author' => 3,
);
$books = new WP_Query( apply_filters(
'wcraleigh_books_query',
$query_args
) );

12. EXAMPLE
add_filter( 'wcraleigh_books_query',
'wcraleigh_modify_book_query'
10,
1
);
function wcraleigh_modify_book_query( $query_args ) {
$query_args['posts_per_page'] = 20;
return $query_args;
}

13. ACTIONS

14. do_action( $tag, $arg_a, $arg_b, $etc );
http://codex.wordpress.org/Function_Reference/do_action

15. EXAMPLE
do_action( 'wcraleigh_books_before' );
echo '<div class="wcraleigh_books">';
while( $books->have_posts() ) : $books->the_post()
echo '<div class="wcraleigh_book">';
do_action( 'wcraleigh_before_book_title', get_the_ID() );
echo '<h3 class="wcraleigh_book_title">' . get_the_title() . '</h3>';
do_action( 'wcraleigh_after_book_title', get_the_ID() );
echo '</div>';
endwhile;
echo '</div>';
do_action( 'wcraleigh_books_after' );

16. INTERNATIONALIZATION

17. EXAMPLE
https://codex.wordpress.org/I18n_for_WordPress_Developers
/*
* Plugin Name: i18n Test
* Author: Ryan Duff
* Text Domain: wcraleigh-demo-plugin
*/
$text = __( ‘This is a test', ‘wcraleigh-demo-plugin’ );
_e( ‘This test will echo', ‘wcraleigh-demo-plugin’ );

18. PLUGIN SETTINGS
http://themeoptions.wordpress.com/

19. Security

20. Security
• Nonce
• Sanitization
• Validation
• Database Queries
https://vip.wordpress.com/documentation/best-practices/security/validating-sanitizing-escaping/
http://codex.wordpress.org/Data_Validation

21. Custom Database Tables
https://pippinsplugins.com/custom-database-api-reasons-for-
custom-tables-and-an-api/

22. Clean Up

23. Caching

24. OTHER CONSIDERATIONS
• Code style
• Documentation
• Errors

25. PLUGIN LICENSE

26. COMMON LICENSES
• GPL v2/v3
• MIT (X11)
• Apache License v2
• WTFPL v2
1) http://wordpress.org/plugins/about/
2) http://www.gnu.org/licenses/license-list.html#GPLCompatibleLicenses

27. PLUGIN HOSTING

28. • WordPress.org
• GitHub
• Both?

29. QUESTIONS?

30. RYAN DUFF
RYAN@FUSIONIZED.COM
@RYANCDUFF