This document discusses best practices for developing WordPress plugins. It recommends that plugins be built as frameworks rather than blueprints, and that they are extensible, use WordPress core APIs, create custom actions and filters, allow overriding templates, and include utility functions. The document warns that plugins need to be kept up to date and that the WordPress repository does not support plugin dependencies. It provides resources for further learning.

1. Plugging into Plugins
Josh Harrison
@joshh

2. About Me
I work for 10up working on awesome
WordPress projects
I have a wife and 3 kids.
I live in St. George UT.
I just finished my backyard after working on it
for 4 months.

3. WordPress Plugins
What comes to mind?

6. "Here is something I
created. Maybe
somebody else will find it
useful."

8. Plugins are
Frameworks
Not Blueprints

11. It’s not about core
plugins, it’s about
plugin developers
making better
plugins.

12. Make your plugins
extensible and be nice to
other developers

13. Use the WordPress Core API.

14. WordPress Core APIs
● Database API
● HTTP API
● Shortcode API
● Transients API
● Shortcode API
And many more....

15. Create your own actions and filters.

16. do_action
if ( $valid_request ) {
if ( $status == 'approve' ) {
// dev can remove or add to
do_action( 'new_user_approve_approve_user' );
} else if ( $status == 'deny' ) {
do_action( 'new_user_approve_deny_user' );
}
}

17. apply_filters
$welcome = sprintf( __( 'Welcome to %s. This
site is accessible to approved users only.
To be approved, you must first register.',
'new_user_approve' ), get_option( 'blogname'
) );
$welcome = apply_filters(
'new_user_approve_welcome_message', $welcome
);

18. Allow theme developers to override
plugin templates.

19. // Include template - can be overriden by a theme!
$template_name = 'wp-core-contributions-widget-template.php';
$path = locate_template( $template_name );
if ( empty( $path ) ) {
$path = WP_CORE_CONTRIBUTIONS_WIDGET_DIR . 'inc/' .
$template_name;
}

20. Create template functions.

21. /**
* Display the permalink for the current post.
*
* @since 1.2.0
* @uses apply_filters() Calls 'the_permalink' filter on
the permalink string.
*/
function the_permalink() {
echo apply_filters('the_permalink', get_permalink());
}

22. Create utility methods.

23. /**
* Creates a redirect post, this function will be useful
for import/exports scripts
* @param string $redirect_from
* @param string $redirect_to
* @param int $status_code
* @since 1.3
* @uses wp_insert_post, update_post_meta
* @return int
*/
public function create_redirect( $redirect_from,
$redirect_to, $status_code ) {
....
}

24. Decisions not options.
Actions and filters are even better.

25. /** If you hardcode a WP.com API key here, all key config
screens will be hidden */
if ( defined('WPCOM_API_KEY') )
$wpcom_api_key = constant('WPCOM_API_KEY');
else
$wpcom_api_key = '';

26. Anything else?

27. Child Plugins
Plugin Mashups

28. Caution
You'll have to keep you plugin up to date

29. Disadvantages
The wordpress.org repository does not support
plugin dependencies
What if a child plugin is installed, should the
parent plugin be installed as well?

30. What can I do now?
● Update your plugins
● Send an update to plugin authors
● Fork it

31. Resources
● Pippin Williamson
● Michael Fields
● Brandon Dove - The Pluggable Plugin
● WordPress Plugins as Frameworks