A straightforward example:

function hello($name)
{
	echo 'hello ' . $name;
}

$var = 'hello';
$var('Abdullah'); // out put 'hello Abdullah'

Next, Lambda-style funcitons or anonymous functions is a functions that created dynamically and store in variable.

Use create_function() to create the functions and there’s two parameters required which the first one is the function arguments and the second one is the function’s body.

$func = null;
$refactor = create_function('$a','return $a * ' . $_REQUEST['factor'] . ';');

if(count($_POST) > 0) {
	$func = create_function('$a','return trim($_POST[$a]);');
} else if(count($_GET) > 0) {
	$func = create_function('$a','return strtoupper($_GET[$a]);');
} else {
	$func = create_function('$a','return 0;');
}

echo '<p>' . $func('file') . '</p>';
echo '<p>' . $refactor(5) . '</p>';