How to write a WordPress plugin.

1. Writing Your
First Plugin
by Mark Jaquith
@markjaquith
markjaquith.com
Saturday, August 21, 2010

2. Assumptions
• You know PHP syntax
• You’re targeting PHP 5
Saturday, August 21, 2010

3. What I want you to learn
• Plugins change what
WordPress does
• They rely on the concepts of
actions and filters
• There are numerous internal
WordPress APIs for you to use
Saturday, August 21, 2010

4. What is a Plugin?
• PHP code that sits in separate
files
• Integrates tightly with
WordPress
• Can add, alter, or remove
functionality
Saturday, August 21, 2010

5. Where?
• wp-content/plugins/name.php
• wp-content/plugins/folder/name.php
• WordPress only looks one level deep
• It looks for .php files with a plugin
header
Saturday, August 21, 2010

6. Plugin Header
“Plugin Name” is required.
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7. Basic Structure
• Build some stuff
• Tell WordPress to use that stuff
when WordPress does certain
stuff
Saturday, August 21, 2010

8. Actions
• Triggered when various things
happen in WordPress core
• “Wakes up” code you’ve
registered against that action
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9. Actions
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10. Actions
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11. Filters
• WordPress passes data to your
code
• Your code optionally changes
the data, then returns it to
WordPress
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12. Filters
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13. Filters
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14. How to organize
your plugin
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17. Prefix
cws_spn_function_name()
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18. Singleton
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19. Singleton variation
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20. Most Important
Action in WordPress
init
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21. Let’s build a plugin!
• Insert mailing address and phone number into a
post or a page
• Use a shortcode... [address]
• Configurable address and phone number
• Option to show phone number by default (or not)
• Ability to override the phone number default
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30. Settings form handle
Setting name
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31. Section
handle
Title
Content
callback
Settings
form handle
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32. HTML id
Title
Content
callback
Settings
form handle
Section handle
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44. http://txfx.net/s/3q
Saturday, August 21, 2010