This document provides an overview of building WordPress plugins, including when code should be placed in functions.php versus a plugin, basic plugin structure, adding custom features like shortcodes and upload types, and tips for testing and getting help. It encourages experimenting with code snippets but knowing your limits, and consulting developers when examples are complex. The goal is to help people get started writing simple plugins.

1. Building your first
WordPress plugin
●
Justin Foell
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Developer at 9seeds
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justin@9seeds.com
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@justinfoell

2. I found some sweet code,
where does it go?
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Let's look at an example: admin bar
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Pitfalls of adding it to functions.php

3. When should code go in a
theme's functions.php?
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One question:
Would you still want the feature if the
theme was changed?
●
If YES, put it in a plugin
● If NO, you can put it in functions.php, but
consider renaming the theme or creating a
child theme to avoid upgrade issues

4. Holy crap! Plugins sound hard!
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Writing a Plugin Documentation
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Let's start with the bare minimum
●
Who knows how to type?
●
You can build a plugin!

5. myplugin.php
<?php
/*
Plugin Name: My Plugin
*/

6. Going beyond WordPress basics
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I can't upload a certain file type
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There's a fix for that: upload types

7. Plugins can be as big or small as
you want
●
If you have a feature that you might want to
turn on/off independently of others:
Put it in it's own plugin
Example: Disable upgrade notice

8. Getting Advanced: shortcode
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“Snippets” are a gateway into WordPress
customization
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Advanced example:
PayPal donation shortcode

9. Other Examples
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Shortcodes in widgets
I'm not sure why the “Text” widget doesn't
do this already – how to fix
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Audience Examples?

10. Be careful out there!
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But don't be afraid to experiment
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Create another WordPress instance to test
●
I havent (yet) seen a “malicious”
WordPress code snippet
●
Some examples may be out of date, overly
complex, or blatantly wrong

11. Knowing your limits
●
Copying & Pasting will probably only get
you so far
●
If an example is very long, there's a chance
it might already be a plugin – look there in
stead
●
Consult you friendly local developer – a
local WordPress meetup (and/or mailing
list) is probably your best bet

12. Thank You!
●
Justin Foell - Developer
●
9seeds.com – professional WordPress
development
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justin@9seeds.com
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Code examples: bit.ly/jf-wclv2012
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Slides: bit.ly/jf-wclv2012-slides