Basic to intermediate skills for WordPress hooks (actions and filters).

1. WordPress Hooks
Actions and Filters
WordCamp San Diego 2012

2. Jeffrey Zinn
ocean goer, wordpress fanboy,
avid backpacker, euro gamer,
soccer hooligan,
voracious coffee drinker
• co-founder of pixel jar
• wordcamp oc co-organizer
• adsanity co-developer
• @jeffreyzinn
• jeff@jzinn.us

3. What are Hooks?
• Actions - Actions are the hooks that the WordPress core
launches at specific points during execution, or when specific
events occur.Your plugin can specify that one or more of its
PHP functions are executed at these points, using the Action
API.
• Filters - Filters are the hooks that WordPress launches to
modify text of various types before adding it to the database
or sending it to the browser screen.Your plugin can specify
that one or more of its PHP functions is executed to modify
specific types of text at these times, using the Filter API.

4. Wait...What are Hooks?
•Actions - Do Stuff
• Filters - Change Stuff

5. Why Hooks?
• Crack into code without editing core files
• Let others alter your work

6. Hypothetical
Let’s say we were desperate for a widget to place in
our sidebar that displays the word “awesome.”

7. Basic Awesome Widget
activate

8. Basic Awesome Widget
sidebar
activate

9. Basic Awesome Widget
sidebar
activate
test

10. Hypothetical
Upon further consideration you realize this widget is
sorely lacking in puppy pictures. Now what? Let’s
look in the code...

11. Basic Widget Code
public function widget( $args, $instance ) {
extract( $args );
$title = $instance['title'];
echo $before_widget;
if ( ! empty( $title ) )
echo $before_title . $title . $after_title;
echo '<h2>awesome</h2>';
echo $after_widget;
}

12. Basic Widget Code
public function widget( $args, $instance ) {
extract( $args );
$title = $instance['title'];
echo $before_widget;
if ( ! empty( $title ) )
echo $before_title . $title . $after_title;
echo '<h2>awesome</h2>';
echo $after_widget;
}

13. Deluxe Awesome Widget
t
wi dge
sam
e

14. Deluxe Widget Code
public function widget( $args, $instance ) {
extract( $args );
$title = apply_filters( 'widget_title', $instance['title'] );
echo $before_widget;
if ( ! empty( $title ) )
echo $before_title . $title . $after_title;
do_action( 'before_awesome_widget' );
echo apply_filters( 'filter_awesome_text', '<h2>awesome</h2>' );
do_action( 'after_awesome_widget' );
echo $after_widget;
}

15. Deluxe Widget Code
public function widget( $args, $instance ) {
extract( $args );
$title = apply_filters( 'widget_title', $instance['title'] );
echo $before_widget;
if ( ! empty( $title ) )
echo $before_title . $title . $after_title;
do_action( 'before_awesome_widget' );
echo apply_filters( 'filter_awesome_text', '<h2>awesome</h2>' );
do_action( 'after_awesome_widget' );
echo $after_widget;
}

16. Deluxe Widget Code
public function widget( $args, $instance ) {
extract( $args );
filter!
$title = apply_filters( 'widget_title', $instance['title'] );
echo $before_widget;
if ( ! empty( $title ) )
echo $before_title . $title . $after_title;
do_action( 'before_awesome_widget' );
echo apply_filters( 'filter_awesome_text', '<h2>awesome</h2>' );
do_action( 'after_awesome_widget' );
echo $after_widget;
}

17. Deluxe Widget Code
public function widget( $args, $instance ) {
extract( $args );
filter!
$title = apply_filters( 'widget_title', $instance['title'] );
echo $before_widget;
if ( ! empty( $title ) )
echo $before_title . $title . $after_title;
action! do_action( 'before_awesome_widget' );
echo apply_filters( 'filter_awesome_text', '<h2>awesome</h2>' );
do_action( 'after_awesome_widget' );
echo $after_widget;
}

18. Deluxe Widget Code
public function widget( $args, $instance ) {
extract( $args );
filter!
$title = apply_filters( 'widget_title', $instance['title'] );
echo $before_widget;
if ( ! empty( $title ) )
echo $before_title . $title . $after_title;
action!
do_action( 'before_awesome_widget' );
filter!
echo apply_filters( 'filter_awesome_text', '<h2>awesome</h2>' );
do_action( 'after_awesome_widget' );
echo $after_widget;
}

19. Deluxe Widget Code
public function widget( $args, $instance ) {
extract( $args );
filter!
$title = apply_filters( 'widget_title', $instance['title'] );
echo $before_widget;
if ( ! empty( $title ) )
echo $before_title . $title . $after_title;
action!
do_action( 'before_awesome_widget' );
filter!
echo apply_filters( 'filter_awesome_text', '<h2>awesome</h2>' );
action!
do_action( 'after_awesome_widget' );
echo $after_widget;
}

20. Actions
(do stuff)
• do_action() - Creates a hook for attaching actions via
add_action()
• add_action() - Hooks a function onto a specific action
created with do_action()
• remove_action() - Removes a function attached to a
specified action hook

21. Actions: do_action()
do_action( $tag, $arg, $extra_arg );
• $tag - (string) (required) The name of the hook you wish to create.
Default: None
• $arg - (mixed) (optional) The list of arguments this hook accepts.
Default: ''
...their code...

22. Actions: add_action()
add_action( $tag, $function_to_add, $priority, $accepted_args );
• $tag - (string) (required) The name of the action you wish to hook onto. Default:
None
• $function_to_add - (callback) (required) The name of the function you wish to be
called. Default: None
• $priority - (int) (optional) How important your function is. Alter this to make your
function be called before or after other functions. Default: 10
• $accepted_args - (int) (optional) How many arguments your function takes. Default: 1
...our code...

23. Deluxe Widget Code
public function widget( $args, $instance ) {
extract( $args );
$title = apply_filters( 'widget_title', $instance['title'] );
echo $before_widget;
if ( ! empty( $title ) )
echo $before_title . $title . $after_title;
do_action( 'before_awesome_widget' );
echo apply_filters( 'filter_awesome_text', '<h2>awesome</h2>' );
do_action( 'after_awesome_widget' );
echo $after_widget;
}

24. Deluxe Widget Code
public function widget( $args, $instance ) {
extract( $args );
$title = apply_filters( 'widget_title', $instance['title'] );
echo $before_widget;
if ( ! empty( $title ) )
echo $before_title . $title . $after_title;
do_action( 'before_awesome_widget' );
echo apply_filters( 'filter_awesome_text', '<h2>awesome</h2>' );
do_action( 'after_awesome_widget' );
echo $after_widget;
}

25. Deluxe Widget Code
public function widget( $args, $instance ) {
extract( $args );
$title = apply_filters( 'widget_title', $instance['title'] );
echo $before_widget;
if ( ! empty( $title ) )
echo $before_title . $title . $after_title;
action! do_action( 'before_awesome_widget' );
echo apply_filters( 'filter_awesome_text', '<h2>awesome</h2>' );
do_action( 'after_awesome_widget' );
echo $after_widget;
}

26. do_action( 'before_awesome_widget' );
which action? which function of ours?
add_action( ‘before_awesome_widget’, ‘puppy’ );
function puppy() {
$src = 'http://placedog.com/g/188/150';
echo '<img src="' . $src . '" />';
}
...in your functions.php script....

27. do_action( 'before_awesome_widget' );
which action? which function of ours?
add_action( ‘before_awesome_widget’, ‘puppy’ );
function puppy() {
$src = 'http://placedog.com/g/188/150';
echo '<img src="' . $src . '" />';
}
...in your functions.php script....

28. do_action( 'before_awesome_widget' );
which action? which function of ours?
add_action( ‘before_awesome_widget’, ‘puppy’ );
function puppy() {
$src = 'http://placedog.com/g/188/150';
echo '<img src="' . $src . '" />';
}
Use a unique function name
...in your functions.php script....

30. Multiple Calls to Action
add_action( ‘before_awesome_widget’, ‘puppy’ );
function puppy() {
$src = 'http://placedog.com/g/188/150';
echo '<img src="' . $src . '" />';
}
add_action( ‘before_awesome_widget’, ‘warning’ );
function warning() {
echo '<p>Warning: puppies!</p>';
}
...in your functions.php script....

31. Multiple Calls to Action
add_action( ‘before_awesome_widget’, ‘puppy’ );
function puppy() {
$src = 'http://placedog.com/g/188/150';
Same
echo '<img src="' . $src . '" />';
Action
}
add_action( ‘before_awesome_widget’, ‘warning’ );
function warning() {
echo '<p>Warning: puppies!</p>';
}
...in your functions.php script....

32. Multiple Calls to Action
add_action( ‘before_awesome_widget’, ‘puppy’ );
function puppy() {
$src = 'http://placedog.com/g/188/150';
Diff. F
Same
echo '<img src="' . $src . '" />';
unctio
Action
}
ns
add_action( ‘before_awesome_widget’, ‘warning’ );
function warning() {
echo '<p>Warning: puppies!</p>';
}
...in your functions.php script....

33. Multiple Calls to Action

34. Multiple Calls to Action
Action: before_awesome_widget
Function: puppy

35. Multiple Calls to Action
Action: before_awesome_widget
Function: puppy
Action: before_awesome_widget
Function: warning

36. Ordering Actions
add_action( ‘before_awesome_widget’, ‘puppy’, 2 );
function puppy() {
$src = 'http://placedog.com/g/188/150';
echo '<img src="' . $src . '" />';
$priority (default 10)
}
add_action( ‘before_awesome_widget’, ‘warning’, 1 );
function warning() {
echo '<p>Warning: puppies!</p>';
}
...in your functions.php script....

37. Ordering Actions

38. Ordering Actions
Action: before_awesome_widget
Function: warning
Priority: 1

39. Ordering Actions
Action: before_awesome_widget
Function: warning
Priority: 1
Action: before_awesome_widget
Function: puppy
Priority: 2

40. Actions: remove_action()
remove_action( $tag, $function_to_remove, $priority, $accepted_args );
remove_action( 'before_awesome_widget', 'warning', 1 );

41. Actions: remove_action()
remove_action( $tag, $function_to_remove, $priority, $accepted_args );
remove_action( 'before_awesome_widget', 'warning', 1 );
Be as specific as
the original action

42. Deluxe Widget Code
public function widget( $args, $instance ) {
extract( $args );
$title = apply_filters( 'widget_title', $instance['title'] );
echo $before_widget;
if ( ! empty( $title ) )
echo $before_title . $title . $after_title;
do_action( 'before_awesome_widget' );
echo apply_filters( 'filter_awesome_text', '<h2>awesome</h2>' );
do_action( 'after_awesome_widget' );
echo $after_widget;
}

43. Deluxe Widget Code
public function widget( $args, $instance ) {
extract( $args );
$title = apply_filters( 'widget_title', $instance['title'] );
echo $before_widget;
if ( ! empty( $title ) )
echo $before_title . $title . $after_title;
do_action( 'before_awesome_widget' );
filter!
echo apply_filters( 'filter_awesome_text', '<h2>awesome</h2>' );
do_action( 'after_awesome_widget' );
echo $after_widget;
}

44. Filters
(change text)
• apply_filters() - Calls the functions added to a filter
hook via
add_filter()
• add_filter() - Hooks a function onto a specific filter
action created with add_filters()
• remove_filter() - Removes a function attached to a
specified filter action hook

45. Filters: apply_filters()
apply_filters( $tag, $value, $var ... );
• $tag - (string) (required) The name of the filter hook.
Default: None
• $value - (mixed) (required) The value which the filters
hooked to $tag may modify.
Default: None
• $var - (mixed) (optional) One or more additional
variables passed to the filter functions.
Default: None

46. Filters: add_filter()
add_filter( $tag, $function_to_add, $priority, $accepted_args );
• $tag - (string) (required) The name of the filter to hook the $function_to_add
to. Default: None
• $function_to_add - (callback) (required) The name of the function to be called
when the filter is applied. Default: None
• $priority - (int) (optional) Used to specify the order in which the functions
associated with a particular action are executed. Functions with the same
priority are executed in the order in which they were added to the action.
Default: 10
• $accepted_args - (int) (optional) Number of arguments the function(s) accept
(s). Default: 1

47. echo apply_filters( 'filter_awesome_text', '<h2>awesome</h2>' );
which filter? which function of ours?
add_filter( ‘filter_awesome_text’, ‘filter_awesome’ );
function filter_awesome( $text ) {
$text .= ‘<h4>puppies</h4>’;
return $text;
}
...in your functions.php script....

48. echo apply_filters( 'filter_awesome_text', '<h2>awesome</h2>' );
add_filter( ‘filter_awesome_text’, ‘filter_awesome’ );
function filter_awesome( $text ) {
$text .= ‘<h4>puppies</h4>’;
return $text;
} Use a unique function name
...in your functions.php script....

49. echo apply_filters( 'filter_awesome_text', '<h2>awesome</h2>' );
add_filter( ‘filter_awesome_text’, ‘filter_awesome’ );
function filter_awesome( $text ) {
$text .= ‘<h4>puppies</h4>’;
return $text;
}
...in your functions.php script....

50. echo apply_filters( 'filter_awesome_text', '<h2>awesome</h2>' );
add_filter( ‘filter_awesome_text’, ‘filter_awesome’ );
function filter_awesome( $text ) {
$text .= ‘<h4>puppies</h4>’;
return $text;
}
always return!
...in your functions.php script....

51. echo apply_filters( 'filter_awesome_text', '<h2>awesome</h2>' );
add_filter( ‘filter_awesome_text’, ‘filter_awesome’ );
function filter_awesome( $text ) {
$text .= ‘<h4>puppies</h4>’;
return $text;
}
always return!
...in your functions.php script....

52. echo apply_filters( 'filter_awesome_text', '<h2>awesome</h2>' );
add_filter( ‘filter_awesome_text’, ‘filter_awesome’ );
function filter_awesome( $text ) {
$text .= ‘<h4>puppies</h4>’;
return $text;
}
add_filter( ‘filter_awesome_text’, ‘second_filter’ );
function second_filter( $text ) {
$text = ‘<h2>dogs!</h2>’;
return $text;
}
...in your functions.php script....

53. echo apply_filters( 'filter_awesome_text', '<h2>awesome</h2>' );
add_filter( ‘filter_awesome_text’, ‘filter_awesome’ );
function filter_awesome( $text ) {
$text .= ‘<h4>puppies</h4>’;
return $text;
}
add_filter( ‘filter_awesome_text’, ‘second_filter’ );
function second_filter( $text ) {
$text = ‘<h2>dogs!</h2>’;
return $text;
}
...in your functions.php script....

54. echo apply_filters( 'filter_awesome_text', '<h2>awesome</h2>' );
add_filter( ‘filter_awesome_text’, ‘filter_awesome’ );
function filter_awesome( $text ) {
$text .= ‘<h4>puppies</h4>’;
return $text;
}
add_filter( ‘filter_awesome_text’, ‘second_filter’ );
function second_filter( $text ) {
$text = ‘<h2>dogs!</h2>’;
return $text;
}
...in your functions.php script....

55. echo apply_filters( 'filter_awesome_text', '<h2>awesome</h2>' );
add_filter( ‘filter_awesome_text’, ‘filter_awesome’ );
function filter_awesome( $text ) {
$text .= ‘<h4>puppies</h4>’;
return $text;
}
add_filter( ‘filter_awesome_text’, ‘second_filter’ );
function second_filter( $text ) {
$text = ‘<h2>dogs!</h2>’;
return $text;
}
...in your functions.php script....

56. echo apply_filters( 'filter_awesome_text', '<h2>awesome</h2>' );
add_filter( ‘filter_awesome_text’, ‘filter_awesome’ );
function filter_awesome( $text ) {
$text .= ‘<h4>puppies</h4>’;
return $text;
}
add_filter( ‘filter_awesome_text’, ‘second_filter’ );
function second_filter( $text ) {
$text = ‘<h2>dogs!</h2>’;
return $text;
}
...in your functions.php script....

57. echo apply_filters( 'filter_awesome_text', '<h2>awesome</h2>' );
add_filter( ‘filter_awesome_text’, ‘filter_awesome’, 2 );
function filter_awesome( $text ) {
$text .= ‘<h4>puppies</h4>’;
return $text;
}
add_filter( ‘filter_awesome_text’, ‘second_filter’, 1 );
function second_filter( $text ) {
$text = ‘<h2>dogs!</h2>’;
return $text;
}
...in your functions.php script....

58. echo apply_filters( 'filter_awesome_text', '<h2>awesome</h2>' );
add_filter( ‘filter_awesome_text’, ‘filter_awesome’, 2 );
function filter_awesome( $text ) {
$text .= ‘<h4>puppies</h4>’;
return $text;
}
add_filter( ‘filter_awesome_text’, ‘second_filter’, 1 );
function second_filter( $text ) {
$text = ‘<h2>dogs!</h2>’;
return $text;
}
...in your functions.php script....

59. echo apply_filters( 'filter_awesome_text', '<h2>awesome</h2>' );
add_filter( ‘filter_awesome_text’, ‘filter_awesome’, 2 );
function filter_awesome( $text ) {
$text .= ‘<h4>puppies</h4>’;
return $text;
}
add_filter( ‘filter_awesome_text’, ‘second_filter’, 1 );
function second_filter( $text ) {
$text = ‘<h2>dogs!</h2>’;
return $text;
}
...in your functions.php script....

60. echo apply_filters( 'filter_awesome_text', '<h2>awesome</h2>' );
add_filter( ‘filter_awesome_text’, ‘filter_awesome’, 2 );
function filter_awesome( $text ) {
$text .= ‘<h4>puppies</h4>’;
return $text;
}
add_filter( ‘filter_awesome_text’, ‘second_filter’, 1 );
function second_filter( $text ) {
$text = ‘<h2>dogs!</h2>’;
return $text;
}
...in your functions.php script....

61. echo apply_filters( 'filter_awesome_text', '<h2>awesome</h2>' );
add_filter( ‘filter_awesome_text’, ‘filter_awesome’, 2 );
function filter_awesome( $text ) {
$text .= ‘<h4>puppies</h4>’;
return $text;
}
add_filter( ‘filter_awesome_text’, ‘second_filter’, 1 );
function second_filter( $text ) {
$text = ‘<h2>dogs!</h2>’;
return $text;
}
...in your functions.php script....

62. remove_filter()
remove_filter( $tag, $function_to_remove, $priority, $accepted_args );
remove_filter( 'the_content', 'wpautop' );

63. Ridiculous Filter
public function widget( $args, $instance ) {
extract( $args );
$title = apply_filters( 'widget_title', $instance['title'] );
echo $before_widget;
if ( ! empty( $title ) )
echo $before_title . $title . $after_title;
do_action( 'before_ridiculous_widget' );
$wrap = ( is_home() ) ? 'h2' : 'h3';
$text = 'awesome';
$pattern = '<%s class="awesome">%s</%s>';
$awesome = sprintf( $pattern, $wrap, $text, $wrap );
echo apply_filters( 'filter_ridiculous_text', $awesome, $wrap, $text );
do_action( 'after_ridiculous_widget' );
echo $after_widget;
}

64. Ridiculous Filter
public function widget( $args, $instance ) {
extract( $args );
$title = apply_filters( 'widget_title', $instance['title'] );
echo $before_widget;
if ( ! empty( $title ) )
echo $before_title . $title . $after_title;
do_action( 'before_ridiculous_widget' );
$wrap = ( is_home() ) ? 'h2' : 'h3';
$text = 'awesome';
$pattern = '<%s class="awesome">%s</%s>';
$awesome = sprintf( $pattern, $wrap, $text, $wrap );
filter!
echo apply_filters( 'filter_ridiculous_text', $awesome, $wrap, $text );
do_action( 'after_ridiculous_widget' );
echo $after_widget;
}

65. Ridiculous Filter
$wrap = ( is_home() ) ? 'h2' : 'h3';
$text = 'awesome';
$pattern = '<%s>%s</%s>';
$awesome = sprintf( $pattern, $wrap, $text, $wrap );
echo apply_filters( 'filter_ridiculous_text', $awesome, $wrap, $text );

66. Ridiculous Filter
$wrap = ( is_home() ) ? 'h2' : 'h3';
$text = 'awesome';
$pattern = '<%s>%s</%s>';
$awesome = sprintf( $pattern, $wrap, $text, $wrap );
echo apply_filters( 'filter_ridiculous_text', $awesome, $wrap, $text );
is_home() !is_home()
<h2>awesome</h2> <h3>awesome</h3>

67. Ridiculous Filter
$wrap = ( is_home() ) ? 'h2' : 'h3';
$text = 'awesome';
$pattern = '<%s>%s</%s>';
??????
$awesome = sprintf( $pattern, $wrap, $text, $wrap );
echo apply_filters( 'filter_ridiculous_text', $awesome, $wrap, $text );
is_home() !is_home()
<h2>awesome</h2> <h3>awesome</h3>

68. echo apply_filters( 'filter_ridiculous_text', $awesome, $wrap, $text );
...assume is_home()...
add_filter( 'filter_ridiculous_text', 'ridiculous_filter', 10, 3 );
function ridiculous_filter( $text, $var1, $var2 ) {
$var2 = "not awesome";
$new = sprintf( '<%s>%s</%s>', $var1, $var2, $var1 );
return $new;
}
...in your functions.php script....

69. echo apply_filters( 'filter_ridiculous_text', $awesome, $wrap, $text );
...assume is_home()...
add_filter( 'filter_ridiculous_text', 'ridiculous_filter', 10, 3 );
function ridiculous_filter( $text, $var1, $var2 ) {
$var2 = "not awesome";
$new = sprintf( '<%s>%s</%s>', $var1, $var2, $var1 );
return $new;
}
...in your functions.php script....

70. echo apply_filters( 'filter_ridiculous_text', $awesome, $wrap, $text );
...assume is_home()...
add_filter( 'filter_ridiculous_text', 'ridiculous_filter', 10, 3 );
function ridiculous_filter( $text, $var1, $var2 ) {
$var2 = "not awesome";
$new = sprintf( '<%s>%s</%s>', $var1, $var2, $var1 );
return $new;
}
...in your functions.php script....

71. echo apply_filters( 'filter_ridiculous_text', $awesome, $wrap, $text );
...assume is_home()... <h2>awesome</h2>
add_filter( 'filter_ridiculous_text', 'ridiculous_filter', 10, 3 );
function ridiculous_filter( $text, $var1, $var2 ) {
$var2 = "not awesome";
$new = sprintf( '<%s>%s</%s>', $var1, $var2, $var1 );
return $new;
}
...in your functions.php script....

72. echo apply_filters( 'filter_ridiculous_text', $awesome, $wrap, $text );
...assume is_home()... <h2>awesome</h2> h2
add_filter( 'filter_ridiculous_text', 'ridiculous_filter', 10, 3 );
function ridiculous_filter( $text, $var1, $var2 ) {
$var2 = "not awesome";
$new = sprintf( '<%s>%s</%s>', $var1, $var2, $var1 );
return $new;
}
...in your functions.php script....

73. echo apply_filters( 'filter_ridiculous_text', $awesome, $wrap, $text );
...assume is_home()... <h2>awesome</h2> h2 awesome
add_filter( 'filter_ridiculous_text', 'ridiculous_filter', 10, 3 );
function ridiculous_filter( $text, $var1, $var2 ) {
$var2 = "not awesome";
$new = sprintf( '<%s>%s</%s>', $var1, $var2, $var1 );
return $new;
}
...in your functions.php script....

74. echo apply_filters( 'filter_ridiculous_text', $awesome, $wrap, $text );
...assume is_home()...
add_filter( 'filter_ridiculous_text', 'ridiculous_filter', 10, 3 );
function ridiculous_filter( $text, $var1, $var2 ) {
$var2 = "not awesome";
$new = sprintf( '<%s>%s</%s>', $var1, $var2, $var1 );
return $new;
}
...in your functions.php script....

75. echo apply_filters( 'filter_ridiculous_text', $awesome, $wrap, $text );
...assume is_home()...
add_filter( 'filter_ridiculous_text', 'ridiculous_filter', 10, 3 );
function ridiculous_filter( $text, $var1, $var2 ) {
$var2 = "not awesome";
$new = sprintf( '<%s>%s</%s>', $var1, $var2, $var1 );
return $new;
}
...in your functions.php script....

76. Examples

77. Genesis Framework

78. Genesis Actions

79. Genesis Filters

80. Other Themes and Plugins?
• WordPress: 790+ actions, 1250+ filters
• Genesis Framework: 180+ actions; 100+ filters
• Gravity Forms: 120+ actions; 270+ filters
• Shopp: 130+ actions; 230+ filters

81. Where Hooks?
• Plugin/Theme Wiki
• Documentation
• Actual Code
(search for do_action and apply_filters)
• Google search!
• http://codex.wordpress.org/Plugin_API

82. Yes, Hooks!
•Actions - Do Stuff
• Filters - Change Stuff

83. do_action( ‘the_end’ )
add_action( ‘the_end’, ‘questions’ );
function questions() {
echo ‘Are there any questions?’;
}
slides: http://slideshare.net/jeffreyzinn/hooks-wcsd12
code: https://gist.github.com/2163780