Plugin Development
- Joey Kudish
http://slides.jkudish.comFriday, 11 January, 13
About me
• WordPress developer since 2007
• Initially built sites for a variety of clients
• Freelance plugin development
• Code Wrangler at WordPress.com / Automattic
since May 2011
• Originally from Montreal, moved to Vancouver
in 2011
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What’s a plugin?
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A plugin extends or modi!es WordPress to do something it
didn’t previously do
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Themes can act as plugins. Oh and there’s
mu-plugins too.
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Plugins can be huge...
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... or tiny.Friday, 11 January, 13
What’s in a plugin?
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Where does it go?
wp-content/plugins/[plugin_name]or wp-content/mu-plugins/
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In order to “hook” into WordPress, we use action and !lter
hooks
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Action hooks allow you to add your own code to WordPress’
call stack
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Filter hooks allow you to modify an
existing variable or piece of information
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Demo time
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Let’s add Google Webmaster Tools
veri!cation to our site
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Finding hooks• WordPress.org Codex (http://
codex.wordpress.org/)
• http://adambrown.info/p/wp_hooks
• Debug Bar + Debug Bar Action Hooks plugin
(http://wordpress.org/extend/plugins/debug-bar-
action-hooks/)
• Search core (use your IDE or a command line
tool like ack)
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Some pro tips
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Use built-in APIs, don’t re-invent the
wheel
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Use WordPress coding standards
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Be nice to other devs. Namespace your classes
and functions. Leave hooks for others.
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Demo time
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hey that’s the !le we want to hook into
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Let’s create our plugin
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It works, now let’s have some fun
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Finished plugin
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A word on Security
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don’t trust users
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sanitize input, escape output
http://codex.wordpress.org/Data_Validation
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protect users from malicious attacks,
use nonces to validate user actions
http://codex.wordpress.org/WordPress_Nonces
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Plugin Distribution
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Further reading
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http://www.wrox.com/WileyCDA/WroxTitle/Professional-WordPress-Plugin-Development.productCd-0470916222.html
http://www.packtpub.com/wordpress-plugin-development-cookbook/book
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Thanks!
Q&Ahttp://slides.jkudish.com
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