Plugin Development - WP Meetup Antwerp

1. Plugin Development
Antwerp WordPress Meetup

2. Hallo, met Barry
WooCommerce Developer @ WooThemes
Related Posts for WordPress
Download Monitor
Post Connector
What The File

3. My Setup
MacBook Pro Retina
PHPStorm
GIT : CLI & SourceTree
Vagrant, Precise32 box, custom provision script

4. Coding Standards

5. Naming Conventions
function some_name( $some_variable ) { [...] }
class Walker_Category extends Walker { [...] }
class WP_HTTP { [...] }
my-plugin-name.php
class-my-class.php

6. PHP standards
if ( condition )
my_function( $parameter )
$array['index']
$array[ $index ]
PHPStorm 8+ supports WordPress code standards : ALT + CMD + L

7. Yoda Conditions
if ( true === $the_force ) {
$victorious = you_will( $be );
}
!
A little bizarre, it is, to read. Get used to it, you will.

8. Databases
Always use the WP API!
$wpdb->prepare( "SELECT * FROM " . $wpdb->posts .
" WHERE `ID` = %d", $id );

9. Tips

10. Debugging
WP_DEBUG
Xdebug

11. Backwards Compatibility
Deprecate instead/before removing

12. Code Templates
Basic plugin in a minute
https://gist.github.com/barrykooij/
abe272917d536fb0f777

13. The Project

14. Open Source ?

15. What if someone steals my code?!

16. What if someone says my code sucks?!

17. Open Source!
Yes, it s definitely scary at first
It s what drives our community
It s the future, not only for code

18. Versioning
Work with major, minor and bug-fix releases (x.y.z)

19. Changelog
Always keep a public changelog
Always include dates in your changelog
Give props to those who deserve it

20. WordPress.org
Repository

21. WP Repository
Use a header image and plugin logo
Have a clear description of what your plugin does
People rate by downloads, ratings AND active
installs(!)

23. Image Specs
Header Image
banner-772x250.jpg
Icon
icon-256x256.png & icon-128x128.png

25. Performance
Write with performance in mind
Bad performance is a deal breaker

26. Object Orientated Programming
Write OO code, period.
Don t know how? Learn it. Believe me, it s worth it.

27. Documentation

28. Code Documentation
Write code documentation, people will love you for it!
Write code documentation directly after the method declaration
You won t forget writing it afterwards
You re making yourself rethink what you function should do
Good IDE s will use the documentation for autocompletion

29. Inline Documentation
Explain what you re doing
Explain why you re doing it

30. Site Documentation
Simple pages
Custom Post Type
HelpScout Knowledge Base

31. Security

32. Sanitizing Data
Checking if data is of an expected structure (e.g. is_email)
Reformatting data so it will be of expected structure (e.g.
sanitize_title)
codex.wordpress.org/Data_Validation#Input_Validation

33. Escaping Data
XSS attacks
esc_url
esc_html

34. Capabilities
User X allowed to do Y?
if ( ! current_user_can( 'manage_options' ) ) {

35. Direct File Access
Prevent direct file access
ABSPATH check

36. if ( ! defined( 'ABSPATH' ) ) {
header( 'HTTP/1.0 403 Forbidden' );
die();
}

37. Internationalization

38. i18n

39. Translatable Plugins
load_plugin_textdomain( 'my-textdomain', false,
dirname( plugin_basename( __FILE__ ) ) . '/languages/' );
!
__( 'My String', 'my-textdomain' );
_e( 'My String', 'my-textdomain' );

40. Translation Files
Generate a .pot file
GlotPress
Transifex

42. Code

43. Hooks
add_action( hook_name , my_hook_callback );
do_action( hook_name );

44. Filters
add_filter( 'filter_name', 'my_filter_callback' );
$new_value = apply_filters( 'filter_name',
$old_value );

45. JavaScript events
$( 'body' ).bind( 'event', function(event, the_value)
{ } );
$( 'body' ).trigger( 'event', [ value ]);

46. Plugin FILE
// Define
define( 'RP4WP_PLUGIN_FILE', __FILE__ );
// Load main plugin file
require_once plugin_dir_path( RP4WP_PLUGIN_FILE ) .
'classes/class-rp4wp.php';

47. Prefix Classes & Methods
WordPress : PHP version 5.2.4 or greater
Namespaces : 5.3.0 or greater
Prefix your classes
class RP4WP_Related_Word_Manager

48. Test your plugin on
PHP 5.2.4

49. Barry Kooij
@CageNL
barrykooij.com