Building a Pluggable Plugin

building pluggable plugins @brandondove #plugplug #wcla

pluggable plugins are... • also known as core plugins • built by a team of developers rather than a single developer • more secure • less buggy • easier to customize than a traditional plugin • supported by original developers • ever changing

their importance... • plugin repository is a mess • instill conﬁdence in users • developers can’t know

OOP concept: inheritance • allows developers to reuse common pieces of code. • class structures help you play nice • helps keep code maintainable

sub base sub sub OOP diagram

cars share basic functionality: driving, steering, lights on/off

class subClass extends baseClass { protected function publish( $obj ) { // method must be defined wp_insert_post( $obj ); } abstract class baseClass { protected function update( $obj ) { // method must be defined abstract protected function publish( $obj ); wp_update_post( $obj ); abstract protected function update( $obj ); } abstract protected function delete( $obj ); protected function delete( $obj ) { public function get_post( $id ) { // method must be defined $post = get_posts( 'p='.$id ); wp_delete_post( $obj ); return $post; } } } } $sub = new subClass; $my_post = $sub->get_post( 1 ); $my_post[0]->post_content = 'Some new content'; $sub->update( $my_post[0] ); $sub->delete( 1 ); PHP5 OOP implementation

WordPress concepts: actions & ﬁlters • actions allow themes and plugins to execute code • ﬁlters allow themes and plugins to modify output • these are what make WordPress REALLY awesome

WordPress actions do_action( 'non_clashing_action_name', $args ); add_action( 'non_clashing_action_name', 'my_hooking_function', (int) priority, (int) arguments ); function my_hooking_function( $args ) { // execute some code here }

class subClass extends baseClass { function __construct() { add_action( 'base_class_publish', array( &$this, 'notify_me' ), 1, 1 ); } protected function publish( $obj ) { do_action( 'base_class_publish', $obj ); wp_insert_post( $obj ); } abstract class baseClass { protected function notify_me( $obj ) { wp_mail( abstract protected function publish( $obj ); 'brandon@pixeljar.net', abstract protected function update( $obj ); 'post published', abstract protected function delete( $obj ); print_r( $obj, true ) ); public function get_post( $id ) { } $post = get_posts( 'p='.$id ); return $post; protected function update( $obj ) {} } protected function delete( $obj ) {} } } $sub = new subClass; $my_post = array( 'post_title' => 'My post', 'post_content' => 'This is my post', 'post_status' => 'publish', 'post_author' => 1, 'post_category' => array( 8, 39 ) ); $sub->publish( $my_post ); PHP5 OOP + WordPress actions implementation

WordPress ﬁlters echo apply_filters( 'non_clashing_filter_name', $args ); add_filter( 'non_clashing_filter_name', 'my_filtering_function', (int) priority, (int) arguments ); function my_filtering_function( $args ) { return htmlentities( $args ); }

class subClass extends baseClass { function __construct() { add_filter( 'base_class_publish', array( &$this, 'i_wrote_this' ), 1, 1 ); } protected function publish( $obj ) { $obj = apply_filters( 'base_class_publish', $obj ); abstract class baseClass { wp_insert_post( $obj ); } abstract protected function publish( $obj ); abstract protected function update( $obj ); protected function i_wrote_this( $obj ) { abstract protected function delete( $obj ); $obj['post_author'] = 2; return $obj; public function get_post( $id ) { } $post = get_posts( 'p='.$id ); return apply_filters protected function update( $obj ) {} ( 'base_class_get_post', $post ); protected function delete( $obj ) {} } } } $sub = new subClass; $my_post = array( 'post_title' => 'My post', 'post_content' => 'This is my post', 'post_status' => 'publish', 'post_author' => 1, 'post_category' => array( 8, 39 ) ); $sub->publish( $my_post ); PHP5 OOP + WordPress ﬁlters implementation

real-world example nextgen gallery

Problem: Solution: We needed an additional function another_image_size( $image ) { image size created to global $ngg; if( !class_exists( 'ngg_Thumbnail' ) ) display in a lightbox within require_once( nggGallery::graphic_library() ); our theme. $image = nggdb::find_image( $image['id'] ); $width = '920'; $height = '560'; if ( !is_writable( $image->imagePath ) ) return ' <strong>'.$image->filename. __( ' is not writeable','nggallery' ).'</strong>'; $file = new ngg_Thumbnail( $image->imagePath, TRUE ); if ( !$file->error ) { $file->resize( $width, $height, 4 ); $image->imagePath = preg_replace( '/(gif|jpg|jpeg|png)/i', 'lightbox.$1', $image->imagePath ); $file->save( $image->imagePath, $ngg->options['imgQuality']); $size = @getimagesize ( $image->imagePath ); $file->destruct(); } else { $file->destruct(); return ' <strong>'.$image->filename. ' (Error: '.$file->errmsg . ')</strong>'; } } add_action( 'ngg_added_new_image', 'another_image_size', 10, 1 ); real-world example: nextgen gallery

real-world example shopp plugin

Problem: Solution: We wanted to use a real- function check_stock( $external, $product ) { time external inventory if( !$stock = ExtInventory::checkStock( $product->ID ) ) return false; tracking system. return $stock; } add_filter( 'shopp_cartitem_stock', 'check_stock', 1, 2 ); real-world example: shopp plugin

real-world example social me

real-world example: social me • custom post types for storing social media content • opt-in extension manager • extensions handle social networks

real-world example: social me twitter • authenticates with oauth • imports tweets as custom post type • custom taxonomies for hash tags and @mentions • post to twitter via actions • changed defaults via ﬁlters

questions?

Brandon Dove @brandondove brandon@pixeljar.net (714) 932-5787 http://pixeljar.net

Building a Pluggable Plugin

by Brandon Dove on Sep 13, 2010

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Building a Pluggable Plugin — Presentation Transcript

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