can I pass arguments to my function through add_action?

Question

can I do something like that? to pass arguments to my function? I already studied add_action doc but did not figure out how to do it. What the exact syntax to pass two arguments would look like. In particular how to pass text & integer arguments.

function recent_post_by_author($author,$number_of_posts) {   some commands; } add_action('thesis_hook_before_post','recent_post_by_author',10,'author,2') 

UPDATE

it seems to me that it is done somehow through do_action but how? :-)

Answer 1

can I do something like that? to pass arguments to my function?

Yes you can! The trick really is in what type of function you pass to add_action and what you expect from do_action.

• ‘my_function_name’
• array( instance, ‘instance_function_name’)
• ‘StaticClassName::a_function_on_static_class'
• anonymous
• lambda
• closure

---

We can do it with a closure.

// custom args for hook  $args = array (     'author'        =>  6, // id     'posts_per_page'=>  1, // max posts );  // subscribe to the hook w/custom args  add_action('thesis_hook_before_post',             function() use ( $args ) {                 recent_post_by_author( $args ); });   // trigger the hook somewhere  do_action( 'thesis_hook_before_post' );   // renders a list of post tiles by author  function recent_post_by_author( $args ) {      // merge w/default args     $args = wp_parse_args( $args, array (         'author'        =>  -1,         'orderby'       =>  'post_date',         'order'         =>  'ASC',         'posts_per_page'=>  25     ));      // pull the user's posts     $user_posts = get_posts( $args );      // some commands     echo '<ul>';     foreach ( $user_posts as $post ) {         echo "<li>$post->post_title</li>";     }     echo '</ul>'; } 

---

Here is a simplified example of a closure working

$total = array();  add_action('count_em_dude', function() use (&$total) { $total[] = count($total); } );  do_action ('count_em_dude' ); do_action ('count_em_dude' ); do_action ('count_em_dude' ); do_action ('count_em_dude' ); do_action ('count_em_dude' ); do_action ('count_em_dude' ); do_action ('count_em_dude' );  echo implode ( ', ', $total ); // 0, 1, 2, 3, 4, 5, 6 

---

Anonymous vs. Closure

add_action ('custom_action', function(){ echo 'anonymous functions work without args!'; } ); //  add_action ('custom_action', function($a, $b, $c, $d){ echo 'anonymous functions work but default args num is 1, the rest are null - '; var_dump(array($a,$b,$c,$d)); } ); // a  add_action ('custom_action', function($a, $b, $c, $d){ echo 'anonymous functions work if you specify number of args after priority - '; var_dump(array($a,$b,$c,$d)); }, 10, 4 ); // a,b,c,d  // CLOSURE  $value = 12345; add_action ('custom_action', function($a, $b, $c, $d) use ($value) { echo 'closures allow you to include values - '; var_dump(array($a,$b,$c,$d, $value)); }, 10, 4 ); // a,b,c,d, 12345  // DO IT!  do_action( 'custom_action', 'aa', 'bb', 'cc', 'dd' );  

---

Proxy Function Class

class ProxyFunc {     public $args = null;     public $func = null;     public $location = null;     public $func_args = null;     function __construct($func, $args, $location='after', $action='', $priority = 10, $accepted_args = 1) {         $this->func = $func;         $this->args = is_array($args) ? $args : array($args);         $this->location = $location;         if( ! empty($action) ){             // (optional) pass action in constructor to automatically subscribe             add_action($action, $this, $priority, $accepted_args );         }     }     function __invoke() {         // current arguments passed to invoke         $this->func_args = func_get_args();          // position of stored arguments         switch($this->location){             case 'after':                 $args = array_merge($this->func_args, $this->args );                 break;             case 'before':                 $args = array_merge($this->args, $this->func_args );                 break;             case 'replace':                 $args = $this->args;                 break;             case 'reference':                 // only pass reference to this object                 $args = array($this);                 break;             default:                 // ignore stored args                 $args = $this->func_args;         }          // trigger the callback         call_user_func_array( $this->func, $args );          // clear current args         $this->func_args = null;     } } 

Example Usage #1

$proxyFunc = new ProxyFunc(     function() {         echo "<pre>"; print_r( func_get_args() ); wp_die();     },     array(1,2,3), 'after' );  add_action('TestProxyFunc', $proxyFunc ); do_action('TestProxyFunc', 'Hello World', 'Goodbye'); // Hello World, 1, 2, 3 

Example Usage #2

$proxyFunc = new ProxyFunc(     function() {         echo "<pre>"; print_r( func_get_args() ); wp_die();     },                  // callback function     array(1,2,3),       // stored args     'after',            // position of stored args     'TestProxyFunc',    // (optional) action     10,                 // (optional) priority     2                   // (optional) increase the action args length. ); do_action('TestProxyFunc', 'Hello World', 'Goodbye'); // Hello World, Goodbye, 1, 2, 3 

Answer 2

Instead of:

add_action('thesis_hook_before_post','recent_post_by_author',10,'author,2') 

it should be:

add_action('thesis_hook_before_post','recent_post_by_author',10,2) 

...where 2 is the number of arguments and 10 is the priority in which the function will be executed. You don't list your arguments in add_action. This initially tripped me up. Your function then looks like this:

function function_name ( $arg1, $arg2 ) { /* do stuff here */ } 

Both the add_action and function go in functions.php and you specify your arguments in the template file (page.php for example) with do_action like so:

do_action( 'name-of-action', $arg1, $arg2 ); 

Hope this helps.