Slides from my WordCamp Orlando 2009 presentation "You're Doing it Wrong".

1. YOU’RE DOING IT WRONG
Chris Scott - @chrisscott - slideshare.net/iamzed
photo by mimk http://www.flickr.com/photos/mimk/222612527/

2. Thanks
• Dion Hulse’s (DD32) two part series on doing it
wrong:
• http://dd32.id.au/2009/11/01/youre-doing-it-
wrong-1/
• http://dd32.id.au/2009/11/01/youre-doing-it-
wrong-2/
• http://dd32.id.au/2009/11/24/how-to-do-it-right-
part-0/
• Michael Pretty for ideas and telling me what I’m doing
wrong
• Sean O’Shaughnessy for ideas and graphics

3. New Features in a Year:
2.7 - 2.8.6
• Sticky posts
• Comment threading and paging
• Widgets API
• Load scripts minified by default
• Load scripts in the footer
• esc_* functions
• security fixes
• and much more...

4. Wrong and Right

5. Not Upgrading
WRONG

6. Upgrading
RIGHT

7. Calling Functions That
Don’t Exist
<div id="sidebar" role="complementary">
<ul>
<li><?php wp_ozh_wsa('mybanner') ?></li>
... rest of sidebar ...
</ul>
</div>
WRONG

8. Check for Functions Before
Calling
<div id="sidebar" role="complementary">
<ul>
<?php if (function_exists('wp_ozh_wsa')) : ?>
<li><?php wp_ozh_wsa('mybanner') ?></li>
<?php endif; ?>
... rest of sidebar ...
</ul>
</div>
RIGHT

9. Hard-Coding WordPress
Paths
$cb_path = get_bloginfo('wpurl')."/wp-content/
plugins/wp-codebox"; //URL to the plugin directory
WRONG

10. Use Constants or Helper
Functions
$cb_path = plugins_url('', __FILE__); //URL to the
plugin directory
RIGHT

11. Echoing Scripts/CSS in
Header/Footer
function codebox_header() {
$hHead .= "<script language="javascript" type=
"text/javascript" src="".get_bloginfo('wpurl')."/
wp-includes/js/jquery/jquery.js"></script>n";
$hHead .= "<script language="javascript" type=
"text/javascript" src="{$cb_path}/js/codebox.js"
></script>n";
print($hHead);
}
add_action('wp_head', 'codebox_header');
WRONG

12. Enqueue Scripts and Styles
function codebox_header() {
wp_enqueue_script(
'codebox',
plugins_url('js/ codebox.js', __FILE__),
array('jquery')
);
}
add_action('template_redirect', 'codebox_header');
RIGHT

13. Not Checking Indices or
Object Properties
if ($_GET['wp125action'] == "deactivate") {
...
}
WRONG

14. Checking Indices/Properties
if (isset($_GET['wp125action']) &&
$_GET['wp125action'] == "deactivate") {
...
}
RIGHT

15. Not Using WP_DEBUG
WRONG

16. Define WP_DEBUG in
wp-config.php
define('WP_DEBUG', true);
RIGHT

17. Using Globals Instead of
Helper Functions/Classes
global $post;
$linkname = get_the_title($post->ID);
WRONG

18. Use Helper Functions/
Classes
$linkname = get_the_title();
RIGHT

19. Writing SQL
global $wpdb;
$wpdb->query("update ".$articles." set review = ".
$rating." where post_id = ".$post_id);
WRONG

20. Use $wpdb Methods
global $wpdb;
$wpdb->update(
$articles,
array('review' => $rating),
compact('post_id')
);
RIGHT

21. Not Validating/Escaping
User Input
<label for="title"><?php echo
get_option('my_plugin_option_title'); ?></label>
<input type="text" id="value" name="value" value="<?
php echo get_option('my_plugin_option_value')); ?>">
WRONG

22. Validate and Escape User
Input
<label for="title"><?php echo
esc_html(get_option('my_plugin_option_title')); ?></
label>
<input type="text" id="value" name="value" value="<?
php echo
esc_attr(get_option('my_plugin_option_value')); ?>">
RIGHT

23. Not Using Caching
$response = wp_remote_get($url);
if (!is_wp_error($response)
&& $response['response']['code'] == '200')
{
$data = $response['body'];
}
... do something with data ...
WRONG

24. Use Caching
if (!$data = wp_cache_get('my_external_data')) {
$response = wp_remote_get($url);
if (!is_wp_error($response) &&
$response['response']['code'] == '200')
{
$data = $response['body'];
wp_cache_set('my_external_data', $data);
}
}
... do something with data ...
RIGHT

25. Not Contributing
photo by TaranRampersad http://www.flickr.com/photos/knowprose/2294744043/
WRONG

26. Contributing
http://codex.wordpress.org/
Contributing_to_WordPress
• Edit the Codex
• Answer Forum Support Questions
• Participate in Development
• Planning, Testing, Bug Reporting and Fixing
• Say “Thanks”
RIGHT