This document provides guidelines for proper plugin and theme development in WordPress. It discusses setting up directory structures and file naming conventions, using namespaces and constants, enqueueing scripts and stylesheets, including separate code files, localization, and using controller classes for activation, deactivation and uninstall hooks. Proper foundation practices like commenting, documentation and readme files are also covered to help developers build well-structured and organized plugins and themes.

1. Laying the Proper
Foundation for Plugin &
Theme Development
WORDCAMP LOUISVILLE 2012

2. Tammy Hart
Designer, front-end developer, and
programmer... I make all the things
Unabashed WordPress addict
Design Engineer at 10up, a premium
WordPress Engineering provider

3. BUILDING BLOCKS
Setting a Standard

4. Structure
Theme and plugins can quickly grow /theme-name
unwieldy. Be prepared with an easy --/css
to understand and simple to use --/fonts
directory structure.
--/images
--/includes
--/js
index.php
functions.php
style.css

5. Commenting
/**
* Returns an unordered list of recent posts
* @param int $numposts Default is 3, can be any integer.
* @param null $author restrict the return to an author
* @param null $tag restrict the return to a tag.
* @param string|array $post_type Default is 'post', define the posts type(s) to return
*
* @return string HTML unordered list
*/
function tcnmy_recent_posts( $numposts = 3, $author = null, $tag = null, $post_type = 'post' ) {
$posts = new WP_Query( array(
'post_type' => $post_type,
'no_found_posts' => true,
'posts_per_page' => intval( $numposts ),
'author' => $author,
'tag' => $tag
) );
...
}

6. Nomenclature
Avoid naming conflicts by // used by core
using unique namespaces. function add_meta_box() { ... }
// too common
function add_a_meta_box() { ... }
// just right!
function themename_add_post_meta_box() { ... }
// class names use Title Case
Follow WordPress core class WP_Query { ... }
standards for class class WP_Rewrite { ... }
naming. class Theme_Name_Do_Stuff { ... }

7. Constants
Save important, static strings in a constant by defining them.
// Set the path constants
define( 'BB_PATH', trailingslashit( dirname( $this->bbconfig ) ) );
define( 'BACKPRESS_PATH' , BB_PATH . 'bb-includes/backpress/' );
define( 'BB_INC', 'bb-includes/' );
// use them
require_once ( BB_PATH . BB_INC . 'class.bb-query.php' );

8. ENQUEUEUEUEUEUE ... UE
Javascript & Stylesheets

9. Why Enqueue?
Can't you just call them in the header.php of a theme or add them there with
actions in a plugin?
NO!
Using enqueue functions makes it easier to
manage scripts, stylesheets, their dependants,
and where they show up.

10. Enqueue Scripts
wp_enqueue_script(
$handle, // name of the script
$src, //where to find it
$deps, // what it depends on to work
$ver, // version number of the script
$in_footer // whether to load it in the footer or not
);
// remove an enqueued script
wp_dequeue_script( $handle );

11. Enqueue Styles
wp_enqueue_style(
$handle, // name
$src, //where to find it
$deps, // what it depends on to work
$ver, // version number of the script
$in_footer // whether to load it in the footer or not
);
// remove an enqueued style
wp_dequeue_style( $handle );

12. Registering
wp_deregister_script( $handle );
wp_register_script(
$handle, // name of the script
$src, //where to find it
$deps, // what it depends on to work
$ver, // version number of the script
$in_footer // whether to load it in the footer or not
);
// now you can just...
wp_enqueue_script( $handle );
// or use it in $deps

13. Put Them in Their Place
ADMIN FRONT END
add_action( 'admin_enqueue_scripts' , add_action( 'wp_enqueue_scripts' ,
'themename_admin_enqueue' ); 'themename_wp_enqueue' );
function themename_admin_enqueue() { function themename_wp_enqueue() {
wp_register_script( ... ); wp_register_script( ... );
wp_register_style( ... ); wp_register_style( ... );
wp_enqueue_script( ... ); wp_enqueue_script( ... );
wp_enqueue_style( ... ); wp_enqueue_style( ... );
if ( get_post_type() == 'page' ) if ( get_post_type() == 'page' )
wp_enqueue_script( ... ); wp_enqueue_script( ... );
} }
More Info: http://bit.ly/enqueue

14. Plugin Example
// Styles and Scripts
add_action( 'admin_enqueue_scripts' , 'recipress_admin_enqueue' );
function recipress_admin_enqueue() {
wp_enqueue_script( 'recipress_back' , RECIPRESS_URL . 'js/back.js' , array( 'jquery',
'jquery-ui-sortable' ) );
wp_enqueue_style( 'recipress_back' , RECIPRESS_URL . 'css/back.css' );
}
add_action( 'wp_enqueue_scripts' , 'recipress_wp_enqueue' );
function recipress_wp_enqueue() {
wp_enqueue_style( 'recipress_front' , RECIPRESS_URL . 'css/front.css' );
}

15. KEEP IT CLEAN
Using Separate Code Files

16. Why Include?
Can't you just dump all your code into functions.php of a theme or the main
plugin file?
Yes, but...
Large amounts of code are easier to read and
edit if they are separated into their own files.

17. Include
// files for themes
include( get_template_directory_uri() . '/includes/some_function.php'
);
// in a plugin
include( CONSTANT_BASE . '/includes/some_function.php' );

18. Include, Require, _once
// Puts the contents of the file directly where it is called
include()
// Only lets the script call the file once
include_once()
// Same as include() but will stop the script if error occurs
require()
// Same as include_once() with the rules of require()
require_once()

19. Plugin Example
// Load plugin files
include_once( RECIPRESS_DIR . 'php/functions.php' );
include_once( RECIPRESS_DIR . 'php/options.php' );
include_once( RECIPRESS_DIR . 'php/meta_box.php' );
include_once( RECIPRESS_DIR . 'php/taxonomies.php' );
include_once( RECIPRESS_DIR . 'php/output.php' );
include_once( RECIPRESS_DIR . 'php/widgets.php' );

20. REMEMBER ALL THE THINGS!
Miscellaneous Memos

21. Theme/Plugin Header
Theme: style.css Plugin: plugin_file.php
/* /*
Theme Name: 10up.com Plugin Name: ReciPress
Author: 10up Plugin URI: http://recipress.com
Author URI: http://10up.com Version: 1.8
*/ */

22. Readme.txt
Used automatically in the WordPress.org repository for things like:
● Stable Tag
● Description
● Installation
● FAQ
● Screenshots
● Changelog
● Update Notice
● Arbitrary Sections
Check your readme: http://wordpress.org/extend/plugins/about/validator

23. Localization
// text strings
__( 'String of Text' , 'text-domain' );
// Echoing text
_e( 'String of Text' , 'text-domain' );
// Explaining text
_x( 'String of Text' , 'A string of text' , 'text-domain' );
// Load the text domain
add_action( 'init', 'plugin_text_domain' );
function plugin_text_domain() {
load_plugin_textdomain( 'text-domain' , false, DEFINED_BASE .
'/lang/' );
}

24. Controls
class WP_Hotfix_Controller {
function init() {
add_action( 'init', 'wp_hotfix_init' );
register_activation_hook( __FILE__, array( __CLASS__, 'activate' ) );
register_deactivation_hook( __FILE__, array( __CLASS__, 'deactivate' ) );
}
function activate() {
add_option( 'hotfix_version' , '1' );
register_uninstall_hook( __FILE__, array( __CLASS__, 'uninstall' ) );
}
function deactivate() {
delete_option( 'hotfix_version' );
}
function uninstall() {
self::deactivate(); // The same, for now
}
}

25. THANK YOU!
Questions?
@tammyhart
10up.com
@10up