Check for anonymous functions in PHP arrays?

Question

How can we check for anonymous functions inside PHP arrays?

Example:

$array = array('callback' => function() {
    die('calls back');
});

Can we then just simply use in_array, and to something like this:

if( in_array(function() {}, $array) ) {
    // Yes! There is an anonymous function inside my elements.
} else {
    // Nop! There are no anonymous function inside of me.
}

I'm experimenting with method chaining and PHP's Magic Methods, and I've come to the point where I provide some functions anonymously, and just want to check if they are defined, but I wish not to loop through the object, nor to use gettype, or anything similar.

Answer 1

You can filter the array by checking if the value is an instance of Closure:

$array = array( 'callback' => function() { die( 'callback'); });
$anon_fns = array_filter( $array, function( $el) { return $el instanceof Closure; });
if( count( $anon_fns) == 0) { // Assumes count( $array) > 0
    echo 'No anonymous functions in the array';
} else {
    echo 'Anonymous functions exist in the array';
}

Pretty much, just check if the element of the array is an instance of Closure. If it is, you have a callable type.

Answer 2

Nickb's answer is great for figuring out if it is an anonymous function, but you may also use is_callable to figure out if it is any type of function ( probably more safe to assume )

For example

$x = function() { die(); }
$response = action( array( $x ) );
...
public function action( $array ){
    foreach( $array as $element )
        if( is_callable( $element ) ) 
           ....
}